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In this article, the mechanics of drag reduction on an axisymmetric body ofrevolution by shallow dimples is presented by using the high-fidelity ReynoldsStress Modeling based simulations. Experimental results of drag evolution frompublished literature at different Reynolds numbers are used to validate themodel predictions. The numerical predictions show good agreement with theexperimental results. It is observed that the drag of the body is reduced by amaximum of $31\%$ with such shape modification (for the depth to diameter ratioof $7.5\%$ and coverage ratio of $52.8\%$). This arises due to the reducedlevel of turbulence, flow stabilization and suppression of flow separation inthe boundary layer of the body. From the analysis of turbulence states in theanisotopic invariant map (AIM) for the case of the dimpled body, we show thatthe turbulence reaches an axisymmetric limit in the layers close to the surfaceof the body. There is also a reduced misalignment between the mean flowdirection and principal axis of the Reynolds stress tensor, which results insuch drag reduction. The dimple depth to diameter and coverage ratio are alsovaried to evaluate its effect on drag evolution.

Mechanics of drag reduction of an axisymmetric body of revolution with shallow dimples