A Full Conservative Approach to Simulate Outflow at Artificial Boundaries

摘要

The proper consideration of flow variables at open boundaries is an important issue in numerical solution of flow fields with inflow and outflow boundary conditions.The issue is so crucial if the outflow conditions are implemented at improper locations such as arbitrary sections which intersect recirculation zones. From finite volume point of view,it is essential to close the boundary volumes in a manner which guarantees the conservation of mass and momentum on all finite volumes including boundary volumes.The idea stems from the fact that improper consideration of the conserve quantities may jeopardize the essence of conservativeness in a finite volume method.In this work,we extend a strategy which fully guarantees the conservation of mass and momentum in the volumes at outlet irrespective of its proper or improper locations.Therefore,to close the outflow control volumes,we employ a new implicit approach which enforces global mass and momentum conservations.A backward-facing step is used to test the extended for- mulation.The results indicate that the extended formulation works excellent although the performance of the original algorithm is slightly deteriorated.