Coral reefs serve as critical habitats for diverse marine species and function as natural barriers against coastal flooding. However, these ecosystems are increasingly threatened by anthropogenic activities and climate change. To mitigate such impacts, bio-mimetic technologies, particularly single bio-mimetic sponges inspired by natural forms, have been proposed as protective interventions for coral reefs. This study investigates the influence of dual bio-mimetic tubular sponges arranged in various configurations (parallel, perpendicular, and at a 45 degrees angle) and spacing on wave-induced hydrodynamics. A three-dimensional Reynolds-Averaged Navier-Stokes (RANS) model employing the standard k-omega SST turbulence closure was utilized to simulate the complex flow dynamics associated with these structures. To enhance visualization and qualitatively illustrate flow patterns and regions of vortical motions, Surface Line Integral Convolution (SurfaceLIC) and three-dimensional stream tracing techniques were applied. The results demonstrate that dual sponge configurations can increase turbulent kinetic energy (TKE) by approximately 50 % while reducing wave energy dissipation by up to 54 %. Image processing analyses further reveal that both the spatial arrangement and interspacing of the sponges significantly influence the morphology of the effluent cloud (EC), which transitions from symmetric, rounded forms to elongated or mirror-imaged patterns. Notably, longitudinal sponge arrangements generate double-paired recirculating vortices, which may exacerbate seabed scouring on sandy substrates. These findings offer novel insights into the hydrodynamic behavior induced by dual bio-mimetic tubular sponges, contributing to a broader understanding of fluid-structure interactions and informing future strategies for coastal ecosystem management.

Coastal areas have historically birthed numerous civilizations. One of the main forcing factors in these regions is spectral waves. Predicting wave characteristics can help protect coastal and marine structures from damage. Recently, several hybrid networks have been proposed to enhance the accuracy of wave characteristics predictions. This study developed a new hybrid network by means of Backpropagation Neural Network (BNN) and Discrete Wavelet Transform (DWT) in a serial configuration. By applying various and flexible functions in DWT, it is anticipated that BNN accuracy would be enhanced. This hypothesis was examined by a dataset from the Busher Port buoy, located in the Persian Gulf (consisted of wind and wave data). The dataset was split into 80

Understanding coral reef hydrodynamics is essential for mitigating the effects of climate change and anthropogenic activities on these ecosystems. The National Oceanic and Atmospheric Administration (NOAA) coral reef conservation program has identified rising ocean temperatures, runoff, and pollutants as major contributors to coral bleaching. Unraveling the complex interactions between marine flow and corals, such as the formation of von-Kármán vortex street, spiral, tip vortices, and horse-shoe vortex, can provide valuable insights for preserving the benthic marine environments. Research indicates that coral morphology affects flow patterns, generating vortices that influence nutrient distribution, larvae transport, and overall ecosystem health. Building upon this understanding, biomimetic approaches have emerged as innovative solutions for coral reef restoration. Designs such as biomimetic sponges, brain corals, branched corals, and artificial reefs enhance upwelling, vortex generation, and resilience, supporting recovery efforts in degraded reefs. Further, this review addresses two key objectives: i) analyzing the internal and external hydrodynamic processes adjacent to coral reefs, and ii) exploring advancements in biomimetic technology inspired by corals and sponges to promote sustainable management as well as restoration of marine ecosystems.

Marine sponges influence the flow hydrodynamics by suction/pumping mechanism. They provide a recirculation flow and remove pollutants from their residence. Previous studies have validated the efficacy of mimetic sponges in improving momentum transfer in marine environments. This study endeavors to explore the impact of wave characteristics (i.e., wave height and period) on the momentum transfer near the mimetic sponges. Both physical and numerical simulations were undertaken to explore this phenomenon. Experimental results unveiled that the efficiency of the mimetic sponge is contingent upon some circumstances. When waves have a short period and height, the suction effects prevail. In such cases, orbital velocity tends to be in a negative direction, leading to suppressed fluctuating velocities and a reduction in turbulent kinetic energy throughout the water column. Thus, the penetration of the shear layer to the water column and occurrence of wake-street diminish. Conversely, an increase in wave height enhances the momentum exchange through the water column. Surface Line Integral Convolution and Three-Dimensional stream trace visualizations using OpenFOAM provide insights into the generation of spirals and vortices through the water column induced by mimetic sponges.

Based on National Oceanic and Atmospheric Administration (NOAA) Coral Reef Conservation Program, climate change causes coral bleaching. In response to the high roughness of coral colonies and reduced current velocity, coral reefs in near-shore regions are susceptible to accumulation of pollutants or sediments. This threatens coral reef ecosystems and causes several challenges. Controlling the wave velocity, Turbulent Kinetic Energy (TKE), and vortical structures help enhance advection/diffusion of particles from coral reef zones. In the current study, a device inspired by a marine sponge (synthetic sponge), was designed. A suction/pumping function was devised through two concentric perforated cylinders to simulate this mechanism in the synthetic sponge. Several physical and numerical experiments (using OpenFOAM software considering RANS modeling) were carried out to investigate the effects of geometrical characteristics (i.e., cylinder and perforation diameters) of synthetic sponge on wave hydrodynamics. Accordingly, wave attenuation, mean horizontal and orbital velocities, turbulent kinetic energy, and vortex structures were evaluated. In summary, the results indicated that the pumping flow can act as an energy recovery downstream of the sponge, and the horizontal velocity and TKE growing in the water column due to generation of special vortices. Therefore, the current synthetic sponge can improve momentum transfer.

Coral reefs consist of various alive elements with specific biological functions. Tubular sponges, as the main coral reefs' constituents, have a marvelous mechanism. They receive nutrients by suctioning from the perforated body (Ostia) and pumping the un-digested materials through the water column from the top mouth (Osculum). This mechanism can be an inspiration for making a device to control or improve sediment/pollutant transport. In the current study, an attempt has been made to evaluate an inspired concept's effects on flow hydrodynamics. In this regard, OpenFOAM® V. 1812 (interFOAM solver) and image processing technique were deployed. The perforated finite-height cylinders (height to diameter ratio of 2.5) with various suction/pump discharges (i.e., J = 150, 300, 350, 400, 450, and 600 lit/h) were considered. The results indicated that increasing the outflow discharge (J ≥ 600 lit/h) could widen the wake by flapping the shear layer. In the vertical plane, the results showed that dipole vortices turned into quadrupole vortex. On the free surface, tip-vortices and counter-rotating vortex pairs (CRVP) generated saw-toothed vortices on two sides of the cylinder. Generating these unique vortices is proof of enhancing the momentum exchange through the water column.

Climate changes and sediment discharge within the oceans trigger many problems, such as coastline erosion and coral reef extinction hazards. Therefore, it is crucial to control wave hydrodynamics in the desired manner to protect marine environments. To prevent the promotion of sedimentation, nature has its response. The tubular sponge is a marvelous animal. It has a perforated body and sucks nutrition and water from these perforations; then, it pumps the undigested materials out from the top outlet. In the current study, an apparatus inspired by natural tubular sponges (synthetic sponges) was designed. The computational fluid dynamics derived from the Reynolds-averaged Navier-Stokes equations and image processing technique (surfaceLIC) was deployed to study how the synthetic sponge affects the wave hydrodynamics. The results revealed that the suction of the body and outflow shielding phenomenon of one sponge reduces the wave transmission by up to ≈7%. In addition, the swing motion of the jet by wave train and effluent cloud generation causes the shear on the sponge. Therefore, the momentum exchange enhances through the water column (≈46% increase of turbulent kinetic energy). It is similar to the swing behavior of flexible vegetation. Furthermore, the surfaceLIC result revealed that the effluent cloud shape changes to a pear shape, symmetric, stretched (transition), and asymmetric by increasing the pumping discharge to 600 L/h. Observing the chute–jet phenomenon by surfaceLIC also proved the diffraction and creation of a low-velocity zone in the shadow region, which is proof of a breaking wave due to the sponge’s suction/pumping and perforated body. Consequently, it can be concluded that a synthetic sponge can act as both rigid and flexible vegetation. The synthetic sponge is anticipated to mitigate sedimentation by creating unique vortices, circulating flow, and its body shape.

Coral reefs are exposed to extinction due to the sediment blocking through coral colonies. In this condition, there is no practical solution that originates from nature. Among all aquatic animals, marine tubular sponges have marvelous mechanisms. These natural creatures can inspire the design of a device for managing sediment-flow hydrodynamics. They suck flow from body perforation and pump water and undigested materials from the top outlet. Therefore, coinciding with receiving nutrients, the flow becomes circulated. This may help the momentum transfer through the coral colonies. In the current study, a synthetic sponge by motivating the tubular sponges was designed. Synthetic sponges' suction/pumping discharge was constant at 150 L/h. They have a body diameter of 8 and 15 cm and a height of 20 cm. The perforation area distribution changes to understand how it may influence sedimentflow hydrodynamics. The numerical modeling based on Reynolds Averaged Navier Stokes (RANS) equations and image processing technique (surface LIC) were deployed to determine the vortical flow patterns. Results confirmed that choosing the best body perforation configuration and area distribution can generate the dipole vortex. In this condition, a tornado combines with dipole and erodes the sediments to z 30% near the bed. Moreover, the sediment concentration reduces to z 20% in the water column at X/D =1. In this condition, it can be observed that the emergence of specific vorticities and recirculations develops the suspension of particles. Therefore, the synthetic sponge with precise design can be practical for enhancing the momentum transferring and preventing pollutant blockage among coral colonies.

Marine tubular sponges use horizontal suction to receive the nutrients from the perforated body and pump the undigested materials from the top mouth. The idea of a synthetic sponge was inspired by the tubular one. It was introduced to manage the sediment-flow hydrodynamics for enhancing sediment transport in coral reefs and access channels. In the current study, synthetic sponge effects on the dilute sediment concentration were investigated numerically. The Mixture method based on Three-Fluids Modeling (TFM) was selected. The effects of pore area distributions (0-0.42) and jet flow discharges (0-7500 L/h) on the sediment concentration were evaluated. The surface Line Integral Convolution (surfaceLIC) was used as an image processing technique to assess the fluid hydrodynamics. The results indicate that the effects of perforation area distribution are more significant than suction/pumping discharges on the sediment concentration (94.87% vs. 5.13% contribution). So increasing the distribution of perforation areas can effectively reduce water turbidity (between 20% and 50%). The combination of the wide re-circulation zone, Counter Rotating Vortex Pair (CRVP), spiral flow, and dipole formation are the reasons for this. Therefore, the combination of vortices facilitates sediment transport due to the unique shape and mechanism of synthetic sponge.

Gypsum mortar is a common building material that can be used especially for plastering the walls. This mortar has three important weaknesses which can limit the gypsum mortar for building and statue construction. First; it has low compressive strength. Second; it has high water absorption, and third; it has low setting time. In the current study, cement, Nano silica, and a superplasticizer with polycarboxylate ether were used for solving the problems. The results showed that using cement with providing C-S-H can improve the mortar strength trend line. The results showed significant growth of 28t h day compressive strength (from 9 MPa to 45 MPa). Using Nano silica increases the compressive strength by making C-S-H dense and decreases the water absorption to 1/3 of the control sample. Consuming polycarboxylate ether causes the uniform dispersion of Nanoparticles through mortar. This even diffusion blocks the pores and reduces their mean dimensions. The ANOVA test was used to find the main effective parameters on the 28t h day compressive strength, water absorption, and setting time. In this regard, Nano silica (49.82% contribution), cement content (56.68% contribution), and superplasticizer (73.10 degrees/0 contribution) have the main roles in compressive strength, water absorption, and setting time, respectively.

The current study focuses on two main goals. First, with the use of construction and demolition (C&D) of building materials, a new aggregate was produced and it was utilized for green concrete production. The compressive strength test confirmed the good function of C&DW aggregate concrete. This concrete did not show significant differences with natural sand concrete. Second, Backpropagation neural network (BNN) was adjusted for C&DW concrete strength prediction at different curing times. Although BNN has good accuracy for strength prediction, due to the importance of 28th day of concrete strength the need to improve the accuracy was felt. So discrete wavelet transform (DWT) was used on BNN and a hybrid network was produced. DWT by filtering the noises can improve the homogeneity of the dataset. The results of DWT-BNN showed that the regression can increase to 98% and the MSE index reduces to 0.001. Continued research has shown that increasing the number of filters to four steps leads to reduced accuracy and increased computational cost. So using DWT-BNN as a hybrid network with one filter can improve prediction ability to the desired level but adding up the number of filters not recommended.

The MgO-Construction and demolition waste Concrete (MCC) is a green construction material that not only uses the reactive MgO characteristics but also helps the sustainable development approach. In the current study, 30%, 40%, 50%, and 60% of C&DW was substituted for natural aggregate. Also, reactive MgO (2% to 6% wt.) of cement was added to the samples as filler. The mechanical properties of the concrete samples were evaluated after 210 days of curing. The results showed that samples with a sand-to-cement ratio (S/C) of 2.5 have a higher compressive strength than samples with S/C = 3. In addition to compressive strength, the stress-strain and peak strain relationships were evaluated for MCC samples. According to GB50010, the MCC was more ductile than natural aggregate concrete (NAC). Furthermore, new models were suggested for the stress-strain and peak stress prediction. The Field Emission Scanning Electron Microscopy (FESEM) images were assisted for finding proof of MCC structural behavior. The results indicated that the shape of the microstructure has direct effects on energy absorption. Therefore, the use of 2% and 4% MgO in concrete specimens at S/C of 3 and 2.5, increase the energy absorption ability of MCC for specific C&DW aggregate portion.

Accumulating construction and demolition waste (C&DW) and the rather high hydration temperature of cement are two problems which affect the environment and mass concrete production, respectively. In this study, the effects of reactive MgO hydration and cement content’s role on the mechanical characteristics of C&DW aggregate concrete were evaluated for finding the suitable solution for solving the above-mentioned problems. In the experimental program, sand to cement ratios of 3 and 2.5 were considered (S/C) and the reactive MgO was 2–6 wt% of cement. Also, two types of experiments such as mechanical and chemical tests were carried out. The compressive strength test showed that by increasing the reactive MgO to 6 wt% of cement, the compressive strength of samples in the S/C of 2.5 is higher than the 3. Also, by increasing the percentage of C&DW aggregate from 30 to 60%, the water absorption of samples increases. In the field emission scanning electron microscopy (FESEM) analysis with cases of 2–6% MgO, 60% C&DW aggregate and S/C of 3, cracks were observed, while they were not detected in samples with S/C of 2.5. The X-ray diffraction (XRD) test, confirmed that the major peak of the patterns in almost every sample was related to calcite and with increase in the MgO content to 6%wt., tricalcium silicate was not formed in both samples with S/C of 2.5 and 3. This study confirm that using C&DW aggregate as concrete is practical for making green concrete and using MgO helps to reduce its hydration temperature.

In this study, considering the importance of dams spillways redesign to provide optimal dimensions, the hybrid of particle swarm optimization, gray wolf optimization (GWO) and direct search optimization meta-heuristic approach were proposed. In this methodology, the total volume of spillway body, which indicates the amount of concrete and cost, is considered as the objective function and height of spillway, the number of cycles, apex length and angle of wall are defined as decision variables. By implementing the proposed model based on the data of the Ute dam labyrinth spillway, the optimal dimensions of spillway were determined and compared with the other studies. The results indicated that the hybrid of meta-heuristic algorithms has a very good performance in generating global optimal values, except that the GWO algorithm has a higher convergence rate. In the proposed method, the optimal dimensions provided by the hybrid algorithm led to saving in concrete and reduction of costs to 64% as compared to the existing design of dam. Investigating the optimal dimension of trapezoidal labyrinth spillway also indicates that these dimensions increase the flow capacity of the spillway to \(15{,}760\,\hbox {m}^{3}{/}\hbox {s}\). Finally, comparison of the optimum dimensions obtained with two trapezoidal and triangular sections showed that the optimal form for labyrinth spillway is triangular and leads to improved spillway hydraulic performance.

In this study, mechanical properties of rock flour mortar were investigated through experimental studies. The tests results were employed to assess compressive strength, water absorption and specific gravity of rock flour mortar in the presence of reactive MgO. The results showed that the use of rock flour-to-cement ratio of 1.5 with 2.5% magnesium oxide had the maximum compressive strength and adding more MgO to mortar could not play an effective role in strength property. Water absorption also increased with increasing amounts of magnesium oxide for almost all of the samples. In this study, the lowest water absorption was 11.16% for the sample containing 2% magnesium oxide and rock flour-to-cement ratio of 2.5. The specific gravity of the samples also increased with an increase in the amount of magnesium oxide which varied between 16.2 and 2.4g/cm(3). The field emission scanning electron microscope and energy-dispersive X-ray spectroscopy tests were also used to verify the results. In addition, backpropagation neural network was used for better parameter estimation. This network showed better precision for predicting the 28th day compressive strength with 0.936 regression.

Millions of tons of waste is produced in the world each year and most of it is not recyclable. Furthermore, recycling waste consumes energy and produces pollution. In addition, accumulation of waste in the suburbs and the disposal of waste are very dangerous for the environment. Using waste material in concrete production is an appropriate method for achieving two goals: eliminating waste and adding positive properties in concrete. Since the green concrete industry is expanding, it is necessary to evaluate concrete that contains waste from all aspects in order to determine its capability. This literature study consists of two parts i.e. the use of waste as a substitute for cement and as a substitute for aggregates. Leading waste material that has been used as substitutes is highlighted and the characteristics of the resulting concrete is evaluated. Among other findings, rubber was found to have improved fire resistance and ductility in concrete and agricultural and PET wastes were successfully used in non-structural concrete, while glass helped to improve thermal stability.

Acrylic polymer that is highly stable against chemicals and is a good choice when concrete is subject to chemical attack. In this study, self-compacting concrete (SCC) made using acrylic polymer, nanosilica and microsilica has been investigated. The results of experimental testing showed that the addition of microsilica and acrylic polymer decreased the tensile, compressive and bending strength of the concrete. The addition of nanosilica and an increase in polymer content increased the bending strength of concrete and decreased the tensile and compressive strengths. Because, in the laboratory, the number of samples were limited and the amount of variation was small, comprehensive results cannot be achieved. With the help of neural networks, estimating any amount within the range of the input data is possible. In this paper, in addition to the experimental results, a backpropagation neural network (BNN) was used to simulate the testing on the strength of self-compacting polymeric concrete. The results showed that the use of the normalized mean squared error, resilient backpropagation training, tangent-sigmoid and log sigmoid transfer functions and five neurons in each hidden layers in a two-layer BNN produced good results with a regression value of 0.95 and error of 0.17.

In this study two phases were considered. In the first phase, demolition of building materials such as concrete, brick, ceramic and tile, and stone were crushed and 30–40% stone, 10–20% ceramic, 5–15% brick, and 50–60% concrete waste were used to produce recycled sand. The initial properties of aggregates such as chemical properties, water absorption, moisture content, density, and abrasion were investigated. In the second phase, the mechanical properties of mortar with substitute of natural aggregates with recycled aggregates from 0 to 100% were examined. In addition, the sand to cement ratio was varied from 2, 2.5, and 3. The results showed that the compressive strength in sand to cement ratio of 3 is higher than other ratios. Water absorption test showed that the use of recycled sand increases the water absorption in all ratios of sand to cement. The flexural strength test showed that the use of 0–40% recycled sand in sand to cement ratio of 2.5 is higher than other specimens, but by increasing the waste to between 50 and 70%, specimens with sand to cement ratio of 3 have higher result. Increasing the recycled sand to 100%, produced higher results for sand to cement of 2. Additionally, backpropagation neural network was used to estimate the mechanical properties of mortar. With regression of up to 70% and mean standard error lower than 0.3, this network has good precision to predict the mortar properties.

Waste concrete is one of the most usable and economic kind of concrete which is used in many civil projects all around the world, and its importance is undeniable. Also, the explanation of constructional process and destruction of them cause the extensive growth of irreversible waste to the industry cycle, which can be as one of the main damaging factors to the economy. In this investigation, with using of constructional waste included concrete waste, brick, ceramic and tile and stone new aggregate was made. Also it was used with different weight ratios of cement in the mix design. The results of laboratory studies showed that the using of the ratio of sand to cement 1 and waste aggregate with 20% weight ratio (W20), replacing of normal aggregate, increased the 28 days compressive strength to the maximum stage 45.23 MPa. In the next stage, in order to develop the experimental results backpropagation neural network was used. This network with about 91% regression, 0.24 error, and 1.41 seconds, is a proper method for estimating results.