Roughness element shape effects on heat transfer and skin friction in rough-wall turbulent boundary layers

A new extension for k– turbulence models to account for wall roughness

“…It is worthwhile mentioning that for both cases the uncertainty in c f is estimated to be about AE10-12% by Hosni et al (1993). Moreover it has to be pointed out that k r is determined using the empirical relation by Dirling (1973), which shows a considerable uncertainty when compared with experimental data, see Fig.…”

“…In this section, we consider the turbulent boundary layer flow over a rough surface of length L ¼ 2:4 m composed of hemispheres of diameter l 0 ¼ 1:27 mm investigated experimentally in Hosni et al (1991Hosni et al ( , 1993. The roughness elements are arranged in staggered arrays and the spacing l 1 of two roughness elements is given by l 1 =l 0 ¼ 2, see Fig.…”

“…The roughness elements are arranged in staggered arrays and the spacing l 1 of two roughness elements is given by l 1 =l 0 ¼ 2, see Fig. 1 in Hosni et al (1993). Following Aupoix and Spalart (2003), the equivalent sand grain roughness k r is computed from the empirical formula in Dirling (1973) k r ¼ ak r;m ; a ¼ 0:0164K 3:78 ; K < 4:93; 139:0K À1:90 ; K > 4:93;…”

Solid—Fluid Systems with Simple, Continuous Interface

“…The effect of the free-stream acceleration on the heat transfer from rough surfaces has been examined by Coleman et al (1981) and Taylor et al (1989). The effect of the roughness shape on the heat transfer has been examined by Hosni et al (1993).…”

Numerical simulation of heat transfer and friction in non-uniform wall roughness lattice with different roughness element shapes

“…been a hot issue (Gawande et al, 2014). Hosni et al (1993) investigated the effects of truncated cone roughened surface and companion hemisphere roughened surface on the heat transfer and friction in rough-wall turbulent boundary layers. They found that the increase of Stanton number for the companion hemisphere roughened surface is about 1.3-1.4 times larger than that for the truncated cone roughened surface.…”