In recent years, tapping the sea for potable water has gained prominence as a potential source of water. Since seawater intake systems are often used in the infrastructure industry, ensuring proper efficiency in different operating conditions is very important. In this paper, CFD modeling is used to show general hydraulic design (flow patterns, stream flow, vortex severities, and pre-swirl) principles and performance acceptability criteria for pump intakes in different conditions. The authors explore scenarios for avoiding or resolving hydraulic problems that have arisen as a result of hydraulic model studies. The results show that the designer should make every effort to avoid small entrance and filtration areas from the basin to the intake forebay bottom, which could result in jet outlet and/or supercritical flow; too small logs at the basin outflow, which could result in high velocity flow jets; and sudden area contractions at the forebay to pump bay junction. There should be enough submergence at the pumps to reduce harmful vortex severities and pre-swirl. Curtain walls, baffles, fillets, and splitters, as well as flow redistributors, can all aid in improving approach flow patterns. Reduced flow separations and eddies will be greatly assisted by rounding corners and providing guide walls. Using a numerical model to figure out what is wrong and how to fix it will help the facility’s costs and maintenance decrease in the long run.

Bottom outlets are significant structures of dams, which are responsible for controlling the flow rate, operation, or removal of reservoir sedimentation. The service gate controls the outlet flow rate, and whenever this gate is out of order, the emergency gate which is located at upstream is utilized. The cavitation phenomenon is one of the common bottom outlets’ problems due to the rapid flow transfer. The present research is a numerical study of the flow pattern in a dam’s bottom outlet for different gate openings by the use of Flow‐3D software and RNG k-ε turbulence model. The investigation is carried out on the Sardab Dam, an earth dam in Isfahan (Iran). The maximum velocity for 100% opening of the gate and Howell Bunger valve is about 18 m/s in the section below the gate, and the maximum velocity for 40% opening of the gate is equal to 23.1 m/s. For 50% opening of the service and emergency gate in the valve’s upstream areas, the desired pressure values are reduced. Moreover, in the areas between the two emergency and service gates, the pressure values are reduced. The possibility of cavitation in this area can be reduced by installing aerators. The flow pattern in Sardab Dam’s bottom outlet has relatively stable and proper conditions, and there are no troublesome hydraulic phenomena such as local vortices, undesirable variations in pressure, and velocity in the tunnel, and there is no flow separation in the critical area of flow entering into the branch.

Shoreline protection remains a global priority. Typically, coastal areas are protected by armoring them with hard, non-native, and non-sustainable materials such as limestone. To increase the execution speed and environmental friendliness and reduce the weight of individual concrete blocks and reinforcements, concrete blocks can be designed and implemented as Articulated Concrete Block Mattress (ACB Mat). These structures act as an integral part and can be used as a revetment on the breakwater body or shoreline protection. Physical models are one of the key tools for estimating and investigating the phenomena in coastal structures. However, it does have limitations and obstacles; consequently, in this study, numerical modeling of waves on these structures has been utilized to simulate wave propagation on the breakwater, via Flow-3D software with VOF. Among the factors affecting the instability of ACB Mat are breaking waves as well as the shaking of the revetment and the displacement of the armor due to the uplift force resulting from the failure. The most important purpose of the present study is to investigate the ability of numerical Flow-3D model to simulate hydrodynamic parameters in coastal revetment. The run-up values of the waves on the concrete block armoring will multiply with increasing break parameter ($0.5<{\mathsf{\xi }}_{\mathrm{m}-1,0}<3.3$) due to the existence of plunging waves until it ($\frac{R_{u2\%}}{H_{m0}}=1.6$) reaches maximum. Hence, by increasing the breaker parameter and changing breaking waves (${\mathsf{\xi }}_{\mathrm{m}-1,0}>3.3$) type to collapsing waves/surging waves, the trend of relative wave run-up changes on concrete block revetment increases gradually. By increasing the breaker index (surf similarity parameter) in the case of plunging waves ($0.5<{\mathsf{\xi }}_{\mathrm{m}-1,0}<3.3$), the low values on the relative wave run-down are greatly reduced. Additionally, in the transition region, the change of breaking waves from plunging waves to collapsing/surging ($3.3<{\mathsf{\xi }}_{\mathrm{m}-1,0}<5.0$), the relative run-down process occurs with less intensity.