A sliding-mesh interface method for three dimensional high order spectral difference solver

In this study a sliding-mesh interface method for three-dimensional unstructured mesh is developed and implemented to the high order spectral difference (SD) solver. The mortar approach is utilized for data exchange on the sliding interface for non-uniform unstructured mesh. The factors affecting the accuracy of the mortar method are analyzed, including mortar number, polynomial degree of mortar, non-uniformity of mortars, and mortar omission in polygon clipping. The method is validated with both inviscid and viscous problems with rotating flows. The numerical results show that the present method is able to retain the high order accuracy of the SD method. The influence of mortar omission in polygon clipping for poor quality complex mesh is discussed and evaluated with several validation problems. The errors with and without mortar omission are compared. The results show that the developed method is reliable and accurate even with mortar omission occurred occasionally in the simulation if the maximum omitted area is less than about 15% of its connected element on the sliding interface.