This paper investigates the Flow structures on the near-and far-wake of a 1/8th scaled simplified heavy vehicle model called Ground Transportation System (GTS) model using a steady-state Reynolds-averaged Navier-Stokes (RANS) with k-ω Shear Stress Transport (SST) turbulence model at Reynolds number (Re) of 1. 6 × 106 and yaw angles (Ψ) = 0o-14o. The current CFD results have been validated using experimental data from the literature. Two crosswind conditions based on the crosswind incidence angle (β) are adopted, β < 90o is called crosswind, and β = 90o (perpendicular to the GTS side surface) is called pure crosswind. Vortex detection scheme based on Ω method and total pressure coefficient (Cpt) contours is used to visualize the wake structure. With Ψ, vortices on the GTS roof take birth as a result of pressure differences between the windward and leeward sides. These vortices grow in size as they travel downstream. The growth in size is related to the Helmholtz theorem of vorticity and Kelvin’s Circulation Theorem. The vortices merged at Z/W >-4 (Z/W = 0 is the GTS rear surface) downstream of the GTS for Ψ = 7. 5o and 14o. The merged vortex dissipates at Z/W >-6 and Z/W >-8 for Ψ = 7. 5o and 14o, respectively. In the pure crosswind condition, the merged vortex attaches to the ground due to the velocity difference between the freestream and the moving computational ground used in the present simulation. At Ψ = 14o, surface streamlines on the GTS surface show the creation of two co-rotating vortices on the windward roof. For the present Ψ, similar Flow structures between the two crosswind conditions are shown. Initial results show that the aerodynamic crosswind stability of a truck is related to the spanwise pressure difference between the windward and leeward surfaces of the truck. Keywords

Introduction: Venous valves are a type of oneway valves which conduct blood Flow toward the heart and prevent its backFlow. Any malfunction of these organs may cause serious problems in the circulatory system. Numerical simulation can give us detailed information and point to point data such as velocity, wall shear stress, and von Mises stress from veins with small diameters, as obtaining such data is almost impossible using current medical devices. Having detailed information about fluid Flow and valves' function can help the treatment of the related diseases. Methods: In the present work, the blood Flow through a venous valve considering the flexibility of the vein wall and valve leaflets is investigated numerically. The governing equations of fluid Flow and solid domain are discretized and solved by the Galerkin finite element method. Results: The obtained results showed that the blood velocity increases from inlet to the leaflets and then decreases passing behind the valve. A pair of vortices and the trapped region was observed just behind the valves. These regions have low shear stresses and are capable of sediment formation. Conclusion: The von Mises stress which is a criterion for the breakdown of solid materials was obtained. It was also observed that a maximum value occurred at the bottom of the leaflets.

The filling of a plane gap with a non-Newtonian fluid under non-isothermal conditions is considered by assuming viscous dissipation and curing reaction induced by the heat supplied through the walls of the gap. The rheology of the medium is described by the modified Cross-WLF model accounting for the effect of temperature, strain rate intensity, and the extent of a chemical reaction on the viscosity. The curing reaction kinetics is determined by the equation based on the n-th order reaction with self-acceleration. The problem is solved numerically using an original computational technique. The curable fluid Flow structure is revealed to include three characteristic zones during the filling process: a fixed layer on the solid wall with a high degree of curing; a central “core” with an almost uniform distribution of characteristics; and a transition zone serving as a "lubricating" layer between two abovementioned zones. The structure is governed by heating of the fluid through the wall, since the heating affects the rheological characteristics of the medium and the rate of the cured layer formation. Analysis of the similarity criteria for the considered Flow conditions shows that the fluid Flows in a creeping regime (Re < 0.01); the temperature distribution is mainly affected by convective heat transfer (Pe > 100); the influence of dissipative heating and exothermic effect of the curing reaction is insignificant. The effect of curing on the mass distribution of the liquid portions entering through the inlet section is shown. The variation of the pressure distribution is analyzed at various Flow conditions.

The micro tube bank model is a commonly used structure in microelectro mechanical cooling systems. Flow across a micro tube bank is a basic benchmark for analyzing Flow resistance and heat transfer capability. In this paper, the Flow around a micro tube bank model was studied both experimentally and numerically. Micro-Particle Image Velocimetry technology was used to measure the Flow field at different inlet Flow rates. The laminar Flow model, S-A model and standard k-ε model were used to calculate the Flow field inside the micro tube bank model. By comparing the results from the three numerical models with the experimental results, there is a certain gap between them can be noted. However, it was found that the standard k-ε model is better than laminar model and S-A model in the comparison between numerical results and experimental results. In conclusion, the standard k-ε model is more suitable for the numerical calculation of the Flow field around a micro scale tube bank model.