The Reynolds number dependence of turbulent channel flow over two irregular rough surfaces, based on scans of a graphite and a gritblasted surface, is studied by direct numerical simulation. The aim is to characterise the changes in the flow in the immediate vicinity of and within the rough surfaces, an area of the flow where it is difficult to obtain experimental measurements. The average roug...

According to a model of the turbulent boundary layer that we propose, in the absence of external turbulence the intermediate region between the viscous sublayer and the external flow consists of two sharply separated self-similar structures. The velocity distribution in these structures is described by two different scaling laws. The mean velocity u in the region adjacent to the viscous sublaye...

The effects of tip-gap size on the tip-leakage vortical structures and velocity and pressure fields are investigated using large-eddy simulation, with the objective of providing guidelines for controlling tip-leakage cavitation and viscous losses associated with the tip-leakage flow. The effects of tip-gap size on the generation and evolution of the end-wall vortical structures are discussed by...

We complement the recently achieved status quo of a self-consistent asymptotic theory: incompressible-flow separation from the perfectly smooth surface of a bluff rigid obstacle that perturbs an otherwise uniform flow in an unbounded domain. Here the globally formed Reynolds number, Re, takes on arbitrarily large values, and we are concerned with a long-standing challenge in boundary layer theo...

We study the flow around tip of a dendritic crystal by an inclined stream viscous incompressible liquid. The shape is chosen accordingly to recent theory [Phil. Trans. R. Soc. A 2020, 378, 20190243] confirmed number experiments and computations 2021, 379, 20200326]. Our simulations have been carried out for 0, 30, 60, 90-degree slope dendrite axis. show that inclination has significant effect o...

in this paper, analysis of fluid flow and heat transfer over the bank of tubes is considered. k-ω sst model is applied for simulation of turbulent flow. in this paper, the improvement of efficiency of a bundle of circular tubes by changing the shape of the cross section of one row of the pipes to the elliptical cross section as an innovative plan is considered. as know, friction factor in turbu...

This paper presents finite volume method based on Reynolds-averaged Navier-Stokes (RANS) equations for computation of 2D axisymmetric flow around bare submarine hull using unstructured grid. The body used for this purpose is a standard DREA (Defence Research Establishment Atlantic) bare submarine hull. Shear Stress Transport (SST) k-ω model has been used to simulate turbulent flow past the hull...

The interaction of the overlying turbulent flow with riblets, and its impact on their drag reduction properties are analysed. In the so-called viscous regime of vanishing riblet spacing, the drag reduction is proportional to the riblet size, but for larger riblets the proportionality breaks down, and the drag reduction eventually becomes an increase. It is found that the groove cross section A(...

Large-eddy simulations described here have included the effect of canopy drag through the depth of a plant canopy. Specifically, we have considered the simulation of flow through a forest. Drag forces enter the simulation with the inclusion of form and viscous drag forces in the momentum equation. In addition, we have carried a variable to represent the kinetic energy (KE) associated with the t...