[01] Ashraf Balabel, Mechanical Engineering Dept., Taif University, Taif, Hawiyya, Ki.

In the present paper, the hydrodynamic instability known as Kelvin-Helmholtz instability is numerically investigated with the application of the level set method. First, the classical Kelvin-Helmholtz instability, which is concerned with the topological changes of interface separating two immiscible, incompressible and inviscid fluids (normally liquid/gas) in irrotational and relative motion, is predicted. Further, as in real flow, the effects of viscosity and surface tension are included. The numerical strategy is based on the solution of Navier-Stokes equations over a regular and structured two-dimensional computational grid using the control volume approach in both phases with a separate manner. The kinematic and the dynamic boundary conditions between the two phases are applied on the interface. The transient evolution of the interface due to the different surface forces is predicted by the level set method. The obtained results showed that the roll-up mechanism starting at the interface is largely affected by the different flow regimes considered. The inclusion of the viscous force can lead to a weakened roll-up mechanism. Moreover, the finite surface tension force can prevent the roll-up mechanism compared with classical Kelvin-Helmholtz instability.

Kelvin-Helmholtz Instability, Level Set Method, Numerical Simulation, Surface Tension, Two-Phase Flow

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