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A Cut-Cell Inspired Immersed Boundary  Solver for Compressible Flows

A Cut-Cell Inspired Immersed Boundary Solver for Compressible Flows

தேதி29th Nov 2021

Time02:30 PM

Venue Google Meet

PAST EVENT

Details

Immersed Boundary Methods (IBM) are a class of computational schemes that employ non-body conforming grids for flow simulations. Generally, the fixed background grid is a Cartesian grid into which the body around which flow is to be determined is immersed. In contrast to the body-fitted grids, implementing boundary conditions is not straightforward. Moreover, the way in which boundary conditions are satisfied leads to a different variety of IB methods. However, compared to the body-fitted structured grids or unstructured grids, these methods offer simplicity in grid generation, and the grid is (largely) independent of the geometry involved. This makes computation cheaper (same grid for design studies for instance) and helps in handling moving body problems with relative ease as compared to the more conventional methods. This can be attributed to the fact that the grid need not be generated time and again. The basic methodology involves identifying the cells in which boundary conditions are to be enforced (implicitly or explicitly), wherein forcing is method-dependent. Furthermore, except for those cells, the existing fluid solver is used for flow simulation for the rest of the grid. In addition, IB methods offer less per-grid-point operation count when compared to other curvilinear body-fitted grids or unstructured grids. The challenges posed are imposing boundary conditions and the effect of the particular boundary treatment on the global accuracy offered by the numerical schemes in the existing solver. Since the body cuts the grid randomly, not all IB methods are expected to offer good mass conservation. Nowadays, the work in IB methods is focused on sharp interface methods, and cut-cell methods, of which cut cell methods offer better mass conservation when compared to their counterparts, while, the sharp interface methods are easy to implement. Both the methods have their own limitations. The aim is to develop a direct forcing method with better mass conservation properties, taking a cue from the cut-cell methods. An Immersed boundary solver will be developed based on a finite volume framework, and the above-described methodology for better mass conservation shall be implemented. Eventually, the idea is to extend the same to three dimensions.

Speakers

Madabushi LNV KasturiRangan

Aerospace Engineering