The laminar-to-turbulent transition of boundary layers induced by isolated threedimensional roughness elements is analyzed by mining a direct numerical simulation database, which covers the variation of many physical parameters, including Mach and Reynolds numbers, and obstacle shape and size. We find that the transition process is approximately controlled by a Reynolds number based on the mome...

rockfill dams are accounted as useful measures in watershed management projects. how-ever, the sediment transport through the rockfill materials, could impact their lifetime duration. previously, researches have been conducted to describe the various hydraulically issues of the flow passing through these structures however; there is no general relationship to estimate the sediment transport rat...

a numerical investigation of forced convection in a channel with hot solid block inside a square porous block mounted on a bottom wall was carried out. the lattice boltzmann method was applied for numerical simulations. the fluid flow in the porous media was simulated by brinkman-forchheimer model. the effects of parameters such as porosity and thermal conductivity ratio over flow pattern and t...

We use numerical methods to study two-dimensional flow passing a square cylinder at low Reynolds numbers, and observe period-1 and -3 vortices behind the cylinder at the same Reynolds number Re. When Re increases from a small number to a critical value Re(c) approximately equal to 320, the system could change from bistability, which maintains the spatial symmetry, to tristability, which breaks ...

This paper investigates the global instability of supersonic ramp flow at Mach number 4.8 at different Reynolds numbers through direct numerical simulations. It is found that a critical Reynolds number exist for the flow to become globally unstable. Transition to turbulent happens downstream of the ramp with strong intermittency and is due to the breakdown of streaky structures fed by instabili...

A physical model for flow characteristics analysis of labyrinth-channel emitter is reconstructed by Reverse Engineering from an injection molded part, and both laminar flow and turbulence models are adopted to simulate the flow state under the condition of low Reynolds numbers. According to the distribution of separation and reattachment points, the onset of transition from laminar to turbulent...

The linear marginal instability of an axisymmetric MHD Taylor-Couette flow of infinite vertical extension is considered. For flows with a resting outer cylinder there is a well-known characteristic Reynolds number even without magnetic field but for sufficiently weak magnetic fields there are solutions with smaller Reynolds numbers so that a characteristic minimum exists. The minimum only exist...