Analytical wall function including roughness corrections

Abstract

Inspired by the work of Aupoix [1, 2] and relying on the analytical wall function of Suga et al. [3], this paper proposes a modified version of the wall model capable of accounting for roughness effects. The thermal correction was enhanced to capture roughness effects due to the increase of the wetted surface of the walls. A derivation of the model adapted to configurations with very large roughness is also proposed. The new model is compared to the former analytical wall function formulation using several rough configurations for which experimental data are available. The validation test cases have been chosen to highlight the improvements brought by the present work.

On the importance of the drag coefficient modelling in the double averaged Navier-Stokes equations for prediction of the roughness effects

“…( 12) had to be adjusted to fit the DNS data whereas no calibration was required when using the present model of eq. (15). Although the approaches to develop those two models completely differ, the main dependencies on the Reynolds number and on the roughness topology are well reproduced in both expressions, as proved in figure 4.…”

“…( 12) out of necessity while no additional geometrical correction is required for the present model of eq. (15). At last, it must be pointed out that coefficient C 2 of eq.…”

“…( 12) or the present model of eq. (15). Before examining the velocity profiles obtained with the two models of eq.…”

“…On the other side are the inexpensive approaches based on the concept of equivalent sand-grain roughness often combined with Reynolds-Averaged Navier-Stokes (RANS) models. These approaches account for the presence of roughness by modifying the wallfunctions [13][14][15] or wall boundary condition [16,17]. These modifications are based on a prescribed quantity, the equivalent sand-grain roughness, that represents the effect of the considered roughness distribution.…”

Sensitivity Analysis of Multistage Compressor Characteristics Under the Spray Atomization Effect Using a CFD Model

“…In this paper, the wall-function method that is widely used in industrial flow problems is adopted instead of paying attention to the details of the viscous sub-layer and 30 < y + < 300. The Scalable wall functions can be consistent solutions for any encrypted grid and avoid the deterioration of computing results when y + < 15 [37]. The total pressure and total temperature at the inlet and the circumferential averaged static pressure at the outlet are given in the boundary conditions of the eight-stage axial compressor.…”