High-speed and accurate simulations of landslide-generated tsunamis are of great importance for the understanding of generation and propagation of water waves and for prediction of these natural disasters. A three-dimensional numerical model, based on Reynolds-averaged Navier–Stokes equations, is developed to simulate the landslide-generated tsunami. Available experiment data is used to validate the numerical model and to investigate the scale effect of numerical model according to the Froude similarity criterion. Based on grid convergence index (GCI) analysis, fourteen cases are arranged to study the sensitivity of numerical results to mesh resolution. Results show that numerical results are more sensitive to mesh resolution in near field than that in the propagation field. Nonuniform meshes can be used to balance the computational efficiency and accuracy. A mesh generation strategy is proposed and validated, achieving an accurate prediction and nearly 22 times reduction of computational cost. Further, this strategy of mesh generation is applied to simulate the Laxiwa Reservoir landslide tsunami. The results of this study provide an important guide for the establishment of a numerical model of the real-world problem of landslide tsunami.

For flood discharge structures with high water heads, aeration facilities are usually installed in engineering to promote water flow aeration and prevent cavitation damage to the overflow surface. Actual engineering has shown that as the slope of the discharge channel bottom decreases or water level changes lead to a decrease in the Froude number, the cavity morphology after conventional aeration facilities or allotype aerators is poor. This article proposes a curved aeration facility scheme based on the idea of locally increasing the bottom slope to reduce the impact angle, which is formed by the convex parabolic bottom plate and concave parabolic bottom plate. The convex parabolic bottom plate is tangent to a flat bottom plate behind the offset, and the concave parabolic bottom plate is tangent to the downstream. The jet landing point is controlled at the junction of the convex parabolic bottom plate and the concave parabolic bottom plate, and the lower jet trajectory is in line with the parabolic bottom plate. The corresponding parabolic bottom plate calculation formulas were theoretically derived, and the design method of the shape parameters of the aeration facility was provided. Through specific engineering case studies, it was found that: (1) As the Z_AC/Z_AG value increases, point C becomes closer to point G, the slope of the water tongue landing point C becomes steeper, and the cavity is less likely to return water. (2) When the position of the water tongue landing point is 0.5–0.8 times the height of the water tongue impact point, there is almost no water accumulation in the calculated cavity. At this time, the platform length L_AB = 0.5L_AF, the convex parabolic section length L_BC = (0.45–0.6) L_AG, the concave parabolic section length L_CD = (0.43–0.11) L_AG, the convex parabolic section calculation formula is z (x) = −A₁x₂ (A₁ = 0.0059–0.00564), and the concave parabolic section calculation formula is A₂x₂ − B₂x₂ (A₂ = 0.003347–0.01927).This solved the problem of aeration and corrosion reduction under small bottom slope, large-unit discharge, and low Froude number engineering conditions.

In the hydraulically suspended passive shutdown assembly, in order to prevent the liquid suspension rod falling too fast and the outer tube from violent impact, it is necessary to study the way to increase flow resistance. This study added grooves to the wall of the narrow channel to increase its flow resistance. Using the RNG k-ε turbulence model in Fluent, the influence of the groove structure parameters and the Reynolds number on the flow resistance of the narrow channel was discussed to find the optimal groove structure parameters. The results showed that the flow resistance of the narrow channel increased with the increase in the concave–convex ratio, and when the concave–convex ratio was small, the flow resistance decreased with increased groove thickness, while when the concave–convex ratio exceeded a certain critical value, the flow resistance increased with increased groove thickness. Additionally, the growth rate slowed down when the concave–convex ratio was greater than 3:1. As the unit length decreased, the flow resistance first increased and then decreased. When the unit length was 6 mm, the flow resistance reached the maximum. With the increase in the Reynolds number, the intensity of the local high-turbulence kinetic energy clearly increased.

This study proposes a design method based on adjoint shape optimization to enhance the heat transfer efficiency of shell-and-tube heat exchangers in oil and gas transportation systems. The primary focus of this work is the design optimization of shell-and-tube heat exchangers through geometric optimization. By simplifying the complex three-dimensional shell-and-tube heat exchanger into a pseudo-three-dimensional reduced-order model, two-dimensional adjoint shape optimization analyses were conducted under unidirectional symmetry about the x-axis and bidirectional symmetry in the x- and y-axes, respectively. The optimized two-dimensional models exhibited a significant increase in the average outlet temperature. Furthermore, the optimized two-dimensional shapes were extruded and reconstructed into three-dimensional models for validation. The results demonstrate that the average air outlet temperature of the three-dimensional models increased by 5.35 K and 3.07 K compared to the original design. Flow field analysis revealed that the heat transfer was improved, since the optimized pipeline layout enhances flow separation and turbulent mixing, leading to a more uniform temperature distribution. This study validates the effectiveness of the adjoint shape optimization method in improving the performance of shell-and-tube heat exchangers.

In this study, friction factor of a fully developed laminar flow in a noncircular duct, which is used in an automotive cooler system, is investigated. The Poisson equation of velocity with homogeneous boundary conditions is solved by using the method of separation of variables and analytical solutions of velocity, wall shear stress and friction factor for arbitrary symmetric noncircular ducts are obtained. The analytical solutions are validated by comparing against analytical and experimental data available for rectangular and triangular ducts. Cross-sectional distribution of velocity, wall shear stress along the duct boundary and friction factor are analysed in depth. It is obtained that the friction factor for this specific duct is $λ=95Re$⁠, with Re defined with equivalent diameter as length scale. Moreover, the applicability of a general equation of friction factor proposed by Duan et al. is validated for this specific duct by comparing with the analytical solution. The result shows that the general equation is accurate enough and can be used for the evaluation of flow resistance in design of the cooler system.

Reservoir-bank landslides may become unstable after reservoir impoundment and generate impulse waves, posing serious threats to hydropower hub structures, reservoir navigation, and downstream safety. The H1 landslide, with a volume of approximately 5.35 million m³, is located on the left bank of the near-dam reservoir area of Yangqu Hydropower Station. Reservoir operation and water-level fluctuations may affect the stability of the H1 landslide; if instability occurs, rapid water entry could generate impulse waves that threaten the hydraulic structures. To evaluate the impulse-wave hazards associated with the H1 landslide, a three-dimensional physical model was constructed at a geometric scale of 1:200. Representative experiments were conducted under landslide instability volumes of 100 × 10⁴, 200 × 10⁴, and 500 × 10⁴, reservoir water levels of 2710.0 m and 2715.0 m, and the corresponding prototype-oriented water-entry conditions. The generation, propagation, opposite-bank run-up, and wave responses in front of the hydraulic structures were investigated. The results show that both the initial wave height near the water-entry point and the wave height in front of the hydraulic structures increase with increasing landslide volume. At the water-entry point, the maximum wave height increases from 3.10–3.27 m for the 100 × 10⁴ m³ landslide to 4.50–4.64 m for the 200 × 10⁴ m³ landslide and further to 7.18–7.21 m for the 500 × 10⁴ m³ landslide. In front of the hydraulic structures, the maximum wave height at the spillway reaches 5.61 m for the 200 × 10⁴ m³ landslide under the ecological restricted water level of 2710 m. After superposition with the wind-wave run-up, the corresponding total wave elevation is 2718.8 m, which remains below both the dam crest elevation of 2721.0 m and the wave-wall crest elevation of 2722.2 m. However, under the normal pool level of 2715 m, the total wave elevations at the spillway and power station intake after superposition with wind-wave run-up exceed the wave-wall crest elevation, indicating a potential overtopping risk. The research results provide a scientific basis for reservoir impoundment scheduling, landslide-generated impulse wave risk prevention, and the safety protection of key hydraulic structures at Yangqu Hydropower Station.