Numerical modeling of a two-dimensional aerated cavitation in a symmetrical venturi nozzle
Résumé
Cavitation is a well-known physical phenomenon occurring in various technical applications. Its coupling with the aeration, is a recent technique, which allows the control of the overall effect of the cavitation. The aeration is achieved by introducing air bubbles into the flow. In order to reveal and explore the behaviour of air in the vicinity of the cavitation regions, the paper is oriented towards the physics of the colliding vapour phase in the presence of cavitation. By penalizing the strain rate tensor in the Homogeneous Equilibrium Model, a two-way cavitation-aeration coupling is achieved. The contact-handling algorithm is based on the projections of the velocity fields of the injected bubbles over the velocity field of the fluid flow. At each time step the gradient of the distance between the bubbles, is kept non-negative, as a guarantee of the physical non overlapping. The bubbles are considered as non-deformable. The differential equations system is composed of the 2D Navier-Stokes equations, implemented with the Homogeneous Equilibrium Model. A high-order Finite Volume solver based on Moving Least Squares approximations is used. The code uses a SLAU-type Riemann solver for the accurate calculation of the low Mach numbers. The computational domain is a symmetrical 2D venturi nozzle, with 18 •-8 • convergent/divergent angles respectively.
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