1er Symposium canadien en analyse numérique et calcul scientifique
Why do numerical shockwaves jump to the wrong conclusions?
Zaide, Daniel W.
University of British Columbia

The reliable simulation of shockwaves is critical in the prediction and study of many phenomena, where abrupt changes in material properties due to shockwaves can greatly affect regions of interest and activate physical mechanisms. When a physical shockwave is formed, it moves through the flow with a certain speed, having some finite width determined by physical dissipation until it encounters some event in its path. For numerical shockwaves, however, a numerical width is enforced, often much greater than the physical width. With this numerical width comes the formation of intermediate states having no direct physical interpretation. Even as the mesh is refined, these intermediate states do not go away; they simply occupy less space. The existence of intermediate states does raise some doubt, however, about how closely a captured shockwave may emulate an ideal discontinuous shockwave, or a real physical one.

There are in fact several types of error associated with intermediate shock states such as errors in shock position, spurious waves, or unstable shock behavior. These errors can be classified as numerical shockwave anomalies; they are numerical artifacts formed due to the presence of captured shockwaves within the flow solution. Each numerical shockwave anomaly is directly related to the nonlinearity of the jump conditions and to a resulting ambiguity in sub-cell shock position in a stationary shock. Two new flux functions are developed that do not have this ambiguity. On all of the shock anomalies in one-dimension, both flux functions show improvement on existing methods without smearing or diffusing the shock.

Lundi, 17 juin, 11h30
Salle Des Plaines C