A study into the techniques needed to accurately predict skin friction using RANS solvers with validation against Froude's historical flat plate experimental data

Download

Preview

PDF - Publishers print Download (1893Kb)

Description/Abstract

This report examines the conditions necessary for the accurate estimation of skin friction using a RANS code flow solver implementing the standard and RNG Κ-є turbulence models. Viscous flow computations were performed for flows over various lengths of flat plate, over a range of Reynolds numbers. The results obtained were validated against Froude's original experimental data and empirical friction lines, and were found to give good agreement at all but the lowest of Reynolds numbers.

A full study was carried out to determine the necessary model and grid parameters needed in obtaining accurate viscous flow solutions. The sensitivity of the flow solutions to changes in boundary position, near wall cell spacing and the total number of grid cells were investigated.

By applying a linear least squares regression fit to the CFD data, a modified Schoenherr skin friction formula was derived, giving a formula with identical gradient and only a slight offset from the original Schoenherr line. An investigation was also carried out to determine how the effects of plate roughness could be simulated in RANS code CFD.