Corpuscular Method for OoP Simulations – Difficulty Dealing with Small Vent Holes

The corpuscular method for airbag deployment simulations in LS-DYNA has quickly gained popularity. The method is inherently stable, easy to use and relatively fast. One drawback, though, is poor handling of small vent holes. The gas flow is underestimated in cases where the particle mean free path is of the same order of magnitude as the vent hole size. In such situations the local flow pattern can not be resolved and the gas has a local behaviour that resembles the one of free molecular flow. This article simply compares the venting as predicted by Wang-Nefske with the venting obtained at free molecular flow. This gives a rough estimate of the worst possible performance of the corpuscular method in the treatment of venting.