Direct numerical simulation was used to study laminar and turbulent flows in circular pipes with smoothly corrugated walls. The corrugation wavelength was kept constant at 0.419D, where D is the mean diameter of the wavy-wall pipe and the corrugation height was varied from zero to 0.08D. Flow rates were varied in steps between low values that generate laminar flow and higher values where the fl...

Some difficulties are encountered when simulating super-critical Reynolds number (Re) flow over curved surfaces of a building in a low speed boundary layer wind tunnel (BLWT) due to the sensitivity of the flow to Re. Surface roughness on the façade of the cylinder can affect the location of the separation point and the extent of the wake on the leeward face, upon which the wind-induced response...

Micro-convection is a strategic area in transport phenomena, since it is the basis for a wide range of miniaturised high-performance applications. Microchannel heat-sinks are appealing solutions to the increasing heat dissipation demands, especially in electronic devices. Literature reveals that in the single-phase continuum regime, the behaviour of micro-convection significantly differs from t...

This paper presents a numerical study of high wavenumber coherent structure evolution in boundary layer transition flow using recently-developed high order Combined compact difference schemes with non-uniform grids in the wall-normal direction for efficient simulation of such flows. The study focuses on a simulation of an Adverse-Pressure-Gradient (APG) boundary layer transition induced by broa...

In this study, the supersonic and choked subsonic flows through micro/nano channels are investigated using direct simulation Monte Carlo (DSMC) method. The supersonic case is simulated at different Knudsen numbers covering slip to transition flow regimes, while the effects of inlet Mach and back pressure are studied in details. The inlet/outlet pressure boundary conditions are suitably implemen...

Almost all computational fluid dynamics (CFD) simulations of flow around marine propellers use turbulence models that are only well suited for fully turbulent flows, which in some cases may lead to accuracy degradation in the prediction of propeller performance characteristics. The discrepancy between computed thrust and torque and corresponding experimental data increases with increasing prope...

Laminar and turbulent natural convection inside concentric spherical shells with isothermal cold and hot boundaries is numerically investigated up to Rayleigh number values Ra 6 10 and Pr = 0.71. The study utilizes direct numerical simulation (DNS), large eddy simulation (LES) and Reynolds averaged Navier– Stokes (RANS) approaches for investigation of the laminar, transitional and fully develop...

Thermo-hydrodynamic performance of hydrodynamically and thermally developing single-phase flow in an array of rectangular mini-channels has been experimentally investigated. The array consists of fifteen rectangular parallel mini-channels of width 1.1±0.02 mm, depth 0.772±0.005 mm (hydraulic diameter 0.907 mm), inter-channel pitch of 2.0 mm, machined on a copper plate of 8.0 mm thickness and ha...

Pressure distributions over a 20° conical forebody are computed by the commercial CFD software ANSYS CFX. Free stream velocity is 30 m/s, Reynolds number based on the forebody base diameter is 0.3×10 6 , and the angle of attack ranges from 10° to 35°. The C-O structural grids are used to compute the entire flow field. The governing equations are steady Reynolds-Averaged Navier-Stokes Equations ...

Direct numerical simulation (DNS) is performed to examine laminar to turbulent transition due to high-frequency secondary instability of stationary crossflow vortices in a subsonic swept-wing boundary layer for a realistic natural-laminar-flow airfoil configuration. The secondary instability is introduced via inflow forcing derived from a two-dimensional, partial-differential-equation based eig...