Drag characteristics of a turbulent boundary layer over a flat plate with transverse square grooves

Ching, C.Y.; Parsons, Bruce

doi:10.1007/s003480050289

Cited by 5 publications

(4 citation statements)

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“…However, the reduction in the friction coefficient starts to decrease, as they become smaller than the large-scale longitudinal vortices. This agrees well with experimental drag characteristic measurements done by Ching et al on a tow tank but for comparable Reynolds numbers [5]. Figure 3 shows a velocity vector plot of the middle triangular groove discussed earlier.…”

Section: Cross-flow Momentum Transfersupporting

confidence: 80%

“…Only validated numerical models can give insight to the underlying physical aspects of such flows. This stipulates undertaking a thorough comparison between the results obtained here and the experimental work conducted by Ching and Parsons [5], which agree favorably thus far.…”

Section: Discussionmentioning

confidence: 99%

“…As with the laminar boundary layer, close to the surface, the horizontal velocity varies linearly with distance, equation (5). For y + ≥ 7 the velocity gradually asymptotes to the well-known law of the wall, obeying equation 6 between y + = 30 and y = 0.1δ, where δ is the total boundary layer thickness.…”

Section: Boundary Layer Resolutionmentioning

confidence: 99%

“…Ching and Parsons [5] studied the drag characteristics of the turbulent boundary layer over flat plates with transverse square grooves using direct drag measurements in a tow tank. They reported little to no reduction in total drag for the cases tested.…”

Section: Introductionmentioning

confidence: 99%

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CFD modeling of turbulent boundary layer flow in passive drag-reducing applications

Bourisli

Al-Sahhaf

2008

Advances in Fluid Mechanics VII

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In this paper, the turbulence boundary layer, velocity and skin friction coefficient characteristics of grooved surfaces are studied. Flow over surfaces with transverse square, triangular and semicircular grooves are numerically modeled via the finite volume method. Comparisons are made on the basis of the grooved surfaces' skinfriction coefficient, normalized by that of a smooth surface, with Reynolds number in the vicinity of 2 × 10 6 . Results show that square grooves are superior to the two other groove geometries in reducing the drag. Viscous damping in all grooves keeps skin friction inside them well below the surface above. However, the interior geometry of square grooves allows them to balance the net inward momentum due to the sudden absence of the wall in a way that minimizes disturbance of the main flow while taking advantage of the restart of the boundary layer. As a consequence to the separation of the boundary layer, an inevitable stagnation point within the groove must exist. Square grooves had the highest such stagnation point along the backward-facing side of the groove. The shortness of the resulting upward boundary layer from the stagnation point to the corner produces smaller near-wall secondary flow motion and more relaxed merger with the main flow. All this contributes to enhanced drag reduction for the described groove structure.

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Section: Cross-flow Momentum Transfersupporting

confidence: 80%

Section: Discussionmentioning

confidence: 99%

Section: Boundary Layer Resolutionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations