OVERSET ADAPTIVE-GRID METHOD WITH APPLICATIONS TO COMPRESSIBLE FLOWS

A new overset adaptive-grid method which combines a solution-adaptive grid method with an overset-grid method is proposed and applied to tra nsonic flows in this paper. The position on which the subgrid is locat ed is adjusted to the region where the gradient of flow properties is large. The solution-adaptive grid method using an elliptic equation is applied to the overset subgrid. Thus the present overset adaptive-gri d method generates the grid adapted twice to the flow solution. Two ne w ideas are also proposed for the basic adaptive-grid method of the el liptic type in this paper. One of the new ideas is to use a modified d istribution of flow property instead of the actual one in order to est imate weighting functions which control grid spacing. The other is a l ocally-variable relaxation parameter technique which locally changes t he relaxation parameter in the Jacobi iteration process according to t he value of the coefficient of the first order derivatives in the elli ptic equation. The present overset adaptive-grid method is applied to transonic flows, and is shown to be very promising, especially for sha rp shock capturing. (C) 1998 Elsevier Science Ltd. All rights reserved .