Farhanuddin Ahmed

Bio: Farhanuddin Ahmed is an academic researcher from Indian Institute of Technology, Jodhpur. The author has an hindex of 1, co-authored 1 publications receiving 1 citations.

Two- and three-dimensional numerical simulations of clap-fling-sweep of hovering insects

Abstract: The importance of three-dimensional effects for flapping wings is addressed by means of numerical simulation. In particular, the clap–fling–sweep mechanism is examined. The flow at the beginning of the downstroke is shown to be in reasonable agreement with the two-dimensional approximation. After the wings move farther than one chord length apart, three-dimensional effects become essential. Two values of the Reynolds number are considered. At Re¼ 128, the spanwise flow from the wing roots to the wing tips is driven by the centrifugal forces acting on the mass of the fluid trapped in the recirculation bubble behind the wings. It removes the excess of vorticity and delays the periodic vortex shedding. At Re ¼ 1400, vortex breakdown occurs past the outer portion of the wings, and multiple vortex filaments are shed into the wake.

A dynamic multi-grid block lattice Boltzmann method for three-dimensional moving boundary problems

Abstract: A three-dimensional numerical framework of a shifting multi-grid block for moving boundaries based on multi-relaxation time lattice Boltzmann method is developed. This work is an extension of our previous two-dimensional algorithm [1] with significant improvements where low-order temporal interpolation has been replaced with a higher-order spatial interpolation scheme. The model has been validated for the cases i.e., sedimentation of a solid sphere in a fluid medium under the action of gravity. The results demonstrate that the moving multi-block improves the resolution of a geometry that reduces the fluctuations registered in velocity and force measurements for the single coarse mesh. This approach offers a substantial advantage in terms of a significant reduction in computational cost as the grid is refined only locally around the moving body as against a fully refined computational domain.