Adequate and uniform airflow within covered outdoor piles is critical for preserving grain quality during storage. Poor airflow uniformity can lead to uneven moisture distribution, temperature gradients, and localized hotspots within the grain mass, creating an environment conducive to the growth of molds, fungi, and insect infestations. Consequently, such compromised storage conditions can lead to significant economic losses for grain elevators and impact the availability and affordability of grain-based products in the market. However, despite considerable literature addressing airflow uniformity in permanent storage structures, aeration system designs for covered outdoor piles have not generally included indepth analyses affecting airflow distribution. This study aimed to investigate the airflow uniformity in covered outdoor piles using computational fluid dynamics (CFD) simulations. A rectangular grain pile, commonly used in Kansas, was modeled using ANSYS Fluent. Various configurations of covered outdoor piles were evaluated regarding airflow velocity and uniformity. The velocity magnitude, vector plots, and contour plots of velocity were used to visualize the air velocity in the different regions of the grain pile. The uniformity index was used to determine the degree of uniformity. Results showed which configuration has better uniformity and less incidence of poor air velocities in the grain mass. By determining the airflow distribution within the grain mass, we can identify potential areas for improvement in the design of covered outdoor piles.

. The effectiveness of fumigation with phosphine is often compromised by suboptimal distribution of the gas. Non-uniformity in fumigant gas distribution can be caused by several factors, including leaks in the grain bin structure, foreign material in the grain, and the placement of the phosphine source material. Many workers in fumigation have stressed that the most important factor is the ability of the grain storage structure to retain the fumigant gas. Phosphine concentration and distribution were studied during field tests with two replications in U.S. corrugated steel bins containing 95 t of hard red winter wheat. Grain bins sold in the U.S. are not fabricated as sealed, airtight structures; thus, the test bins were sealed following recommendations to close any openings in the structure through which fumigant gas can leak out as best possible, and phosphine was then applied by conventional probe-only and probe and tarp techniques and by closed loop fumigation (CLF) in the testing. Contour plots of phosphine movement showed leakage and uneven distribution over time with conventional probed tablets, resulting in some areas in the lower half of the grain mass receiving a zero dose and other locations remaining below the target phosphine concentration of 200 ppm for the entire fumigation period. This gas distribution monitoring information can be used to improve subsequent treatments by determining sealing quality, to determine if additional gas needs to be applied to a treatment, or if treatment was likely to be unsuccessful, and follow-up treatments are needed. With CLF, phosphine concentrations were uniform throughout the bin levels at each time step, but the measured average phosphine concentration levels were lower than those measured with conventional fumigation. This observation indicates that leakage was higher in CLF in this study than in conventional fumigations, likely due to the recirculation fan pressure. CLF has the potential to achieve more uniform fumigant distribution and is expected to achieve effective concentration levels when implemented in a well-sealed structure.

The movement ofgrain in large quantities generates grain dust, which poses significant health and safety hazards. We investigated the effects of repeated transfers, soybean grade, and bucket elevator feeding direction on soybean dust quantity, particle size, and shape characteristics. Two pilot-scale bucket elevators with differentfeeding configurations, front-feed and back-feed, were used to evaluate soybean dust characteristics, including particle size (circle equivalent diameter), particle size distribution, and shape characteristics (high sensitivity circularity, aspect ratio, and elongation). Dust samples were collected at multiple points on the elevators using glass fiber filters with a cassette assembly and air sampling pump. Particle size and shape analyses were performed using the Malvern Morphologi G3 SE via 2D imaging. A general decreasing trend in dust quantity was observed across both elevator types and soybean grades (U.S. No. 1 and U.S. No. 3). Repeated transfers significantly influenced key dust characteristics, including dust mass, particle size (CE diameter and D[V,0.50]), high sensitivity circularity, aspect ratio, elongation, solidity, convexity, and particulate matter fractions (PM4 and PM10). These findings enhanced the understanding of the effects of repeated handling on soybean dust characteristics, providing important values and insights for modeling dust detachment, suspension, generation, and explosion risks in grain elevators.

Highlights The pseudo-first order kinetic model fits well with the experimental data of sorbed phosphine versus time. Sorption isotherm curves were developed using Langmuir, Freundlich, and Redlich-Peterson models. Phosphine adsorption capacity of wheat kernels increased with increase in applied concentration (400-2400 ppm). Abstract. Phosphine (PH 3 ) is the most used fumigant in the U.S. due to its low price, ease of use, and wide accessibility. With the growing concerns of phosphine-resistant insect pests, the sustainability of PH 3 as an effective fumigant has been put at risk. Sorption equilibrium data is critical for improving the accuracy of modeling studies for phosphine-wheat fumigation systems and would clarify the PH 3 uptake and sorption capacity of wheat. The objectives of this study were to determine the effect of initial concentration (from 400 to 2400 ppm) on the equilibrium concentration for PH 3 in wheat kernels and on cumulative and daily PH 3 sorption through time. Kinetic data showed the sorption process was time-dependent and occurred in two phases: an initial faster adsorption phase, followed by a phase with a slower sorption rate as the grain and PH 3 reached equilibrium. Pseudo-first and pseudo-second order models were fit to PH 3 concentrations versus time experimental data. The pseudo-first order model provided better equilibrium estimates and was used for the sorption isotherm analysis. Langmuir, Freundlich, and Redlich-Peterson sorption isotherm models were fit to the plot of equilibrium headspace gas concentration versus sorbed PH 3 quantity. All three models had low standard errors of prediction (0.46-0.47). These PH 3 sorption kinetics and values of total sorbed quantity at equilibrium are valuable for modeling the rate and maximum quantity of PH 3 uptake in wheat. Keywords: Fumigation, Kinetics, Phosphine, Sorption Isotherm, Wheat.

Highlights A steady state, laminar CFD model was developed to simulate the airflow inside an aerosol exposure chamber. The CFD model predicted the droplet tracks and deposition of various sizes of aerosol droplets. Larger aerosol droplets had higher deposition efficiency. A Higher flow rate, but still within the laminar flow regime, caused lower deposition efficiency for all droplet sizes. Abstract. Aerosol insecticides (e.g., pyrethrin) are widely used for the control of stored products insects inside food facilities. To optimize pyrethrin aerosol application, computational fluid dynamics (CFD) was used to predict airflow and aerosol transport inside a vertical flow aerosol exposure chamber operated under laminar flow conditions. A discrete phase model in ANSYS FLUENT 2021 R1 was developed, and simulations were conducted to track pyrethrin droplets of various diameters (0.1 to 20 µm) and determine their deposition onto Petri dishes located near the center of the chamber. The deposition efficiency of the different aerosol droplet sizes and the effect of two flow rates (5 × 10 -4 m 3 s -1 and 4 × 10 -4 m 3 s -1 ) on deposition efficiency were determined. The results showed that the predicted deposition of pyrethrin aerosol increased with increasing droplet size, largely due to inertial and gravitational effects. Deposition efficiencies decreased with the higher flow rate—with 0.1% to 96.6% predicted deposition efficiencies for the low flow rate and 0.1% to 93.8% for the high flow rate. Results of this study can be used to improve aerosol application methods for stored product insect control. Keywords: Aerosol deposition, Aerosol insecticide, Computational fluid dynamics, Confused flour beetle, Deposition efficiency, Discrete phase model, Numerical simulation, Particle tracking, Pyrethrins, Stored product insect.

. Aerosol insecticides (e.g., pyrethrin) are widely used for the control of stored products insects inside food facilities. To optimize pyrethrin aerosol application, computational fluid dynamics (CFD) was used to predict airflow and aerosol transport inside a vertical flow aerosol exposure chamber operated under laminar flow conditions. A discrete phase model in ANSYS FLUENT 2021 R1 was developed, and simulations were conducted to track pyrethrin droplets of various diameters (0.1 to 20 mu m) and determine their deposition onto Petri dishes located near the center of the chamber. The deposition efficiency of the different aerosol droplet sizes and the effect of two flow rates (5 x 10-4 m3 s-1 and 4 x 10-4 m3 s-1) on deposition efficiency were determined. The results showed that the predicted deposition of pyrethrin aerosol increased with increasing droplet size, largely due to inertial and gravitational effects. Deposition efficiencies decreased with the higher flow rate-with 0.1% to 96.6% predicted deposition efficiencies for the low flow rate and 0.1% to 93.8% for the high flow rate. Results of this study can be used to improve aerosol application methods for stored product insect control.

. Phosphine (PH3) is the most used fumigant in the U.S. due to its low price, ease of use, and wide accessibility. With the growing concerns of phosphine-resistant insect pests, the sustainability of PH3 as an effective fumigant has been put at risk. Sorption equilibrium data is critical for improving the accuracy of modeling studies for phosphine-wheat fumigation systems and would clarify the PH3 uptake and sorption capacity of wheat. The objectives of this study were to determine the effect of initial concentration (from 400 to 2400 ppm) on the equilibrium concentration for PH3 in wheat kernels and on cumulative and daily PH3 sorption through time. Kinetic data showed the sorption process was time-dependent and occurred in two phases: an initial faster adsorption phase, followed by a phase with a slower sorption rate as the grain and PH3 reached equilibrium. Pseudo-first and pseudo-second order models were fit to PH3 concentrations versus time experimental data. The pseudo-first order model provided better equilibrium estimates and was used for the sorption isotherm analysis. Langmuir, Freundlich, and Redlich-Peterson sorption isotherm models were fit to the plot of equilibrium headspace gas concentration versus sorbed PH3 quantity. All three models had low standard errors of prediction (0.46-0.47). These PH3 sorption kinetics and values of total sorbed quantity at equilibrium are valuable for modeling the rate and maximum quantity of PH3 uptake in wheat.

Highlights Develop a CFD model that reveals the detailed mechanisms of phosphine movement in bunkers. Evaluate factors that impact phosphine distribution in grain bunkers. Provide recommendations for best management practices for phosphine fumigation in bunkers. Abstract. Bunker storage is an inexpensive and, thus, popular method for medium- and long-term storage of wheat. To control insect infestations in bunker storage, phosphine (PH3) fumigant, released from aluminum phosphide (AlP) tablets, is commonly used, especially in Australia. For fumigation to be effective, a lethal concentration of PH3 throughout the bunker must be ensured. Because bunkers are exposed to ambient conditions, temperature gradients are created throughout the bunker, resulting in natural convection currents that move PH3 from areas around the fumigation points to the entire bunker. This research used computational fluid dynamics (CFD) simulation to investigate the effect of natural convection on fumigation in bunkers. The model was validated against published benchmarks and a field experiment with a full-scale bin with sorption and leakage. The effects of PH3 release points location, bunker shape, bunker orientation, leakage, sorption, ambient temperature fluctuation, and PH3 motion in 3D were studied. Results agreed well with the experimental data and provided various recommendations for best management practices for PH3 fumigations in bunkers. Results showed that diffusion and natural convection solely are insufficient in spreading out PH3 within bunkers. Further research is needed on the effects of tarpaulin billowing in relation to PH3 behavior. Keywords: Bin, Bunker, CFD, Fumigation, Natural convection, Phosphine, Porous media, Simulation, Sorption, Species transport, Wheat.

Highlights The pressure dependent bulk density relationship was evaluated for nine crops. Two compressibility models were proposed, with RMSE ranging from 1.7 to 7.1 kg m-3, depending on the crop. Differences between compressibility equations had minimal influence on packing predictions in full size bins. Combined test weight and packing correction factors are shown for each crop in bins of different sizes and construction. Abstract. Knowledge of the pressure-dependent bulk density increase observed in stored grains and oil seeds, commonly referred to as packing or compressibility, is important for maintaining accurate grain inventory, evaluating wall loads, and other applications that require estimating density at specific depths in a bin. This study presents compressibility equation parameters determined utilizing a compilation of the best data available, including previously published and new datasets. In all, confined uniaxial compression tests for nine crops (barley, canola, corn, oats, rice, sorghum, soybeans, hard red winter wheat, and soft red winter wheat) were included. The data was fit using two candidate compressibility equations, both of which generally fit well and resulted in root mean squared errors ranging from 1.7 to 7.1 kg m-3, depending on the model and crop. For crops with full scale bin data available from previous research, the resulting equations were applied to estimate inventory and were compared with the measured mass of grain in the bin. Results from both equations were similar, and apart from oats, median errors were less than 2.5%. Keywords: Bulk density, Compressibility, Pack factor, Grain storage, Test weight, Stored grain inventory.

Bulk handling behavior of grains can be studied experimentally, but large-scale investigations of grain flow especially at the commercial scale are expensive, time consuming, and are therefore limited in the treatment factors that can be evaluated in any one study. Recent research has demonstrated the potential of discrete element method (DEM) in simulating grain flow in handling operations. However, application of DEM for simulating grain flow, requires development of appropriate particle models for each grain type. In this study, particle models comprised of one to four overlapping spheres were developed for shelled corn and tested. With these models, measurement of bulk properties, namely bulk density and angle of repose, both involving bulk flow were simulated using EDEM™ software with published data of material and interaction properties of shelled corn as inputs associated with each particle shape. Predicted time for the complete outflow from the bulk density test hopper (hopper emptying time), designated as simulation time in the study, was also recorded as another discriminant for model selection. Variable inputs into the simulation modeling were material properties particle shape, particle size distribution, Poisson's ratio, shear modulus, and density and interaction properties particle coefficients of restitution, static friction, and rolling friction. Computation time is critical in DEM modeling so single sphere particle models were emphasized over multi-sphere particles in the research even though multi-sphere particles represent the corn kernel shape more precisely because their simplicity can provide markedly reduced computation times to complete simulations. Predicted results for hopper emptying time, bulk density, and angle of repose were compared to experimental results or published data to select the most appropriate particle models for simulating bulk behavior of corn kernels in free-flowing grain applications using DEM. From the study, the most appropriate particle model (particle shape/physical properties combination) for corn kernels involved a single-sphere shape particle shape with a particle coefficient of restitution of 0.30, particle coefficients of static friction of 0.30 for corn-corn contact and 0.20 for corn-steel contact, particle coefficient of rolling friction of 0.05, normal particle size distribution with a standard deviation factor of 0.4, and particle shear modulus of 20 MPa.

Chlorine dioxide (ClO2) gas, known for its high oxidation and penetration capacity, is a potential alternative fumigant to control stored-product insect pest population. In this study, hard red spring wheat (Triticum aestivum L.) kernels were exposed to varying levels of gaseous ClO2 concentrations (200, 300, 400, and 500 ppm, 1 ppm = 0.0027 mg/L at room condition) and held in a gas-tight bucket assembly for 24 h after achieving desired concentration. ClO2 treatment achieved complete insect mortality of lesser grain borer (Rhyzopertha dominica (Fabricius)) and highest adult progeny reduction at 500 ppm across all vial locations. Significant reduction (37.8-51.1%) in germination percentage resulted after exposure to 300-500 ppm. Flour lightness value significantly increased after kernel treatment at 200-500 ppm. The pH value of wheat flour was significantly reduced from 6.2 to 6.1 after 500 ppm treatment. Peak and final viscosities of wheat flour significantly decreased from 3303.7 to 3073.3 cP, and from 3515.0 to 3208.3 cP, respectively. No significant difference was observed in other investigated flour quality and functionality parameters, including falling number, trough viscosity, breakdown viscosity, starch damage, and Mixolab dough behavior properties. Overall, ClO2 treatment at 500 ppm is effective in killing adult lesser grain borers without negatively affecting wheat flour quality parameters.

Dust explosions can occur when the dust exceeds its minimum explosible concentration (45e150 g m(-3)) in the presence of confinement, oxidiser, dispersing agent, and an ignition source. These components have long been documented in the literature but studies on dust properties that affect suspension in confined spaces, such as flowability and floodability, are lacking. To address this, dust samples from five grain types (wheat, maize, soybean, rice, and milo) with particle size <450 mm were obtained and tested using five replicates for mean particle size, particle size distribution, and various shape characteristics (high sensitivity circularity, convexity, elongation, solidity, and aspect ratio) using Morphologi G3. Flowability and floodability indices were determined using Carr indices chart based on aerated and packed bulk density measurements; angles of repose, spatula, fall, and difference; compressibility; cohesion; and dispersibility in the Hosokawa Powder Tester PT-R. Results showed significant differences in packed bulk density, cohesion, elongation, and aspect ratio among the five grain dust types. Soybean dust exhibited the highest flowability (34.70) and floodability (64.25) indices suggesting the need for rotary seals to prevent dust from escaping which may further lead to dispersion into confined spaces, while milo dust exhibited the lowest (flowability index, 11.60; floodability index, 9.70). A very strong positive correlation was observed between dispersibility and floodability index and a very strong negative correlation between cohesion and flowability index. The results of the study contributed to the understanding of grain dust properties and their release into the atmosphere. Quantifying these properties is important for creating better grain handling procedures for improved health and safety. (c) 2022 IAgrE. Published by Elsevier Ltd. All rights reserved.

HighlightsSingle kernel mass and particle density were not significantly affected by the number of rice weevils feeding within a corn kernel and lesser grain borers feeding within a wheat kernel.In both corn and wheat, single kernel mass decreased after the larval stage of internally feeding insects.Particle density increased linearly with insect age for both rice weevils in corn and lesser grain borer in wheat.The increasing particle density while the kernel mass was being eroded indicates that the kernel internal void was detected by the gas pycnometer employed for measurement of the true volume of grain kernels.Abstract. To model the dynamics of insect infestation in a grain handling system using the discrete element method (DEM), physical properties of the infested kernels compared to their sound counterparts are needed, specifically particle density and single kernel mass of infested kernels. Thus, the objective of this study was to determine the particle density and single kernel mass of internally infested kernels as affected by insect age. Corn and wheat were infested with internal feeders: rice weevil (RW), Sitophilus oryzae (L.), in corn and lesser grain borer (LGB), Rhyzopertha dominica (F.), in wheat. The internal feeders were allowed to grow and mature inside the kernels and properties were measured for representative samples selected using X-ray imaging approximately 14, 28, 35, and 42 days after the end of a 4-day oviposition period. The measured kernel physical properties were not affected by the number of internal insects per kernel. In both corn and wheat, single kernel mass decreased after the larval stage of internally feeding insects. Single kernel mass decreased from 374 mg in sound corn to 346 mg in corn with pre-emerged RW adults and from 31.4 mg in sound wheat to 25.9 mg in wheat with pre-emerged LGB adults. Particle density increased with insect age for both RW in corn and LGB in wheat with a linear trend. The increasing particle density while the kernel mass eroded indicates that kernel internal void was detected by the gas pycnometer employed for measurement of the true volume of grain kernels. Data obtained from this study enables effective DEM modeling of grain commingling of insect-infested and sound grain kernels in grain handling systems. Keywords: Corn, Insect age, Internal feeders, Insect infestation, Lesser grain borer, Particle density, Rice weevil, Single kernel mass, Wheat.

HighlightsThe predicted bulk density of two wheat varieties varied with drop height, similar to the experiments.The percentage composition of three kernel size fractions in the wheat varieties affected the bulk density.Accurate particle shape representation simulated the heap profile better but required longer computational time.The single-sphere model is more practical to use because of its higher accuracy and lower computational cost.Abstract. Grain bulk density varies widely depending on kernel properties and handling practices. The discrete element method (DEM) can model such behavior at the particle level, including wide-ranging interactions with equipment. The objective of this study was to develop a DEM model to predict wheat bulk density as affected by grain drop height and kernel size distribution. The bulk density of two wheat varieties was measured experimentally for a range of drop heights with a modified test weight per bushel apparatus and was simulated in EDEM v2018.1 using single-sphere and five-sphere particle models that accounted for three kernel size fractions. For both particle models, simulations matched the observed behavior, showing a bulk density increase with increasing drop height and bulk density differences between varieties due to different kernel size fractions. The single-sphere particle model predicted the bulk density with higher accuracy than the five-sphere particle model, while the five-sphere model, which more accurately represented the shape of wheat kernels, allowed better simulation of the heap profile at the cost of longer computation time. These particle models can be used to simulate bulk density of wheat under compaction and to improve prediction models of grain pack factor for wheat. Keywords: Bulk density, DEM, Drop height, Size distribution, Wheat.

Highlights This study developed a mathematical relationship accounting for the production rate of phosphine. The effect of temperature on phosphine sorption into wheat is described mathematically. A computational fluid dynamics (CFD) model was built to predict the phosphine concentration in fumigated grain. Experiments were conducted to validate the CFD model. Abstract . Phosphine gas (PH3) is widely used as a fumigant for stored product insect infestations due to its relatively low price and the near absence of residual chemical on the grain. Understanding the behavior of phosphine gas inside the fumigated space is crucial to maintaining a lethal dosage and protecting stored grain from subsequent insect damage. Phosphine is available either in gas form or is produced from a solid material, as pellets or tablets, that reacts with water in the air. The solid form is the most commonly used; however, limited information is available on the rate of phosphine gas generated from the solid material. In this study, a mathematical equation was formulated, based on previous studies in the literature, to describe the gas generation rate. This equation was incorporated into a computational model using ANSYS Fluent 19.1, a commercial software for computational fluid dynamics (CFD) analysis. The computational model developed here allows prediction of the phosphine concentration within a fumigated grain bulk. The PH3 sorption was included in the model. The effect of temperature on the sorption rate was investigated based on published data, and the rate change due to temperature was characterized. The gas generated by a single pellet was measured in laboratory experiments in a 0.208 m3 sealed barrel. The measurements confirmed the CFD results with an error of 0.3%, 0.9%, and 7.2% for three different configurations. The deviations seen between the experimental replicates increased the error and show the need for further investigation of the effects of temperature, grain age and history, leakage, and other factors. Keywords: CFD, Evolution rate, Phosphine, Sorption.

HighlightsHandheld sprayers generated larger droplets and wider droplet size distributions than compressed gas sprayers.Sprayers with higher pressure and nozzles with wider spray angle produced smaller droplets.Droplet size distribution influenced spray coverage, mass concentration, deposition, and sprayer efficacy.The handheld sprayers had less spray coverage and efficiency than the compressed gas sprayers.The deposition at different locations was influenced by the volume of the space, aerosol dosage, and spray time.Abstract. Aerosol insecticides, including pyrethrins, can be used as methyl bromide replacements to control stored product insects inside flour mills and rice mills. The effectiveness of aerosol application for insect control requires knowing the spray characteristics of the equipment to be used and understanding factors that influence the effectiveness of insecticide application. The objectives of this study, as part of efforts to optimize aerosol applications, were to evaluate the characteristics of six aerosol delivery systems (two handheld sprayers and compressed gas sprayer systems fitted with two types of manifolds and two types of nozzles), estimate the dispersion and deposition of aerosol in a simulated stored product facility, and determine how the dispersion and deposition are affected by the characteristics of the sprayers. Results showed that the spray systems differed significantly in spray characteristics. The compressed gas sprayers generated significantly smaller droplets, more uniform droplet size distribution, and better spray coverage than the handheld sprayers. The ellipsoidal nozzle produced significantly smaller droplets than the circular nozzle. While the type of manifold had no significant effect on deposition, higher aerosol dosage and spray time resulted in significantly higher deposition. Results of this study will be used to improve spray techniques for stored product insect control, to validate computational fluid dynamics modeling of aerosol application, and to improve testing methods in large-scale spray testing inside commercial facilities. Keywords: APS spectrometer, Droplet size distribution, HELOS KR-Vario, Mass deposition, Spray characteristics, Spray nozzles.

HighlightsFreshly harvested, higher quality corn samples have a higher proportion of small dust particles with a lower circularity and aspect ratio compared to older, lower quality samples.For freshly harvested grain, dust particles removed at low centrifuge speed were significantly rougher than particles removed at high speed.Lower quality corn did not show a significant decrease in particle roughness for strongly attached dust.The surface area decreased while the surface energy increased with the attachment strength of dust particles.Abstract. High dust concentrations associated with grain handling can cause serious problems, including health and safety risks from dust inhalation and increased risk of explosions due to contained suspended dust in the presence of an ignition source. The amount of dust generated during grain handling is influenced by several factors, including the adhesion strength of dust to the grain. One factor that could influence the adhesion strength of grain dusts is how the dust particles are shaped and how their shape relates to the surface texture of corn. To better understand the properties of dust particles separated from corn samples, dust samples were analyzed for morphology and particle size. In addition, dust samples were separated with different centrifugation speeds to compare the properties of dusts that were strongly or weakly attached to the grain. These samples were observed with a light profilometer to measure their surface roughness characteristics. Results showed that freshly harvested corn samples contained a higher presence of small particles with low circularity than older, lower quality samples. The large particles observed were determined to be starch, as opposed to the smaller particles that were more likely soil or other non-plant-based material. The dust particles that were more strongly attached to corn kernels tended to have lower surface roughness than those that were weakly attached for the freshly harvested grain. Keywords: Dust adhesion, Particle shape, Surface adhesion, Surface roughness.

HighlightsDecreasing aspect ratio and improved geometrical smoothness of particles increased DEM-predicted bulk density of wheat.Among the three particle models, the 5-sphere ellipsoidal particle was the best option to represent wheat particles, as indicated by the simulated bulk densities that best agreed with the experiments.Among the contact parameters, the wheat-to-wheat coefficient of static friction and wheat-surface coefficient of rolling friction had the greatest influence on simulated bulk density.Abstract. The discrete element method (DEM) has been shown to be an effective tool for simulating the behavior of granular material. The accuracy of simulations depends highly on the contact models, particle physical parameters, and contact parameters used. The objectives of this study were to determine the influence of particle shape and contact parameters on simulated wheat bulk density and to develop an effective wheat particle model for DEM simulation of filling a container using EDEM software. Grain characteristics, including single-kernel weight, kernel density, kernel dimensions, aspect ratio, and bulk density, were determined for three size fractions of wheat used in the experiments. Three categories of particle models (5-sphere pseudo-ellipsoidal, 7-sphere pseudo-ellipsoidal, and ASG-generated) with varying aspect ratios and geometrical smoothness were tested in the simulations. Results showed that DEM-simulated bulk density of wheat increased with lower aspect ratio and greater geometrical smoothness of pseudo-ellipsoidal particles (7-sphere versus 5-sphere). Increasing the number of spheres to approximately 30 for better representation of wheat kernel shape, using ASG-generated particles, did not reproduce the trend of greater simulated bulk density seen in the experiments. Among the six contact parameters, the wheat-wheat coefficient of static friction and wheat-surface coefficient of rolling friction had the most significant effect on the simulated bulk density. Among the different sets of particle models, the 5-sphere pseudo-ellipsoidal particles, having aspect ratios close to that of wheat kernels in each size fraction, were found to be the most practical and appropriate particle model for use in DEM simulation of wheat bulk density. This study contributes to better understanding of the influence of particle shape and contact parameters on DEM-simulated bulk density and provides a calibrated particle model for use in simulating container filling operations. Keywords: Bulk density, Contact parameters, DEM, Particle shape, Wheat.