A NEW PRESCRIPTION FOR VISCOSITY IN SMOOTHED PARTICLE HYDRODYNAMICS

Smoothed particle hydrodynamics (SPH) is a particle method for modelli ng hydrodynamical flows that has been successfully applied to a wide r ange of astrophysical problems. One of its main weaknesses, however, h as been its inability to treat viscosity in a rigorous manner. We pres ent a new method that can be used to solve the Navier-Stokes equation for an arbitrary viscosity. We compare the accuracy of the method to a lternative methods for treating viscosity in SPH, and apply the method to a series of tests for which there exist analytic solutions. We fin d that the new method is significantly more accurate than other existi ng methods, computationally efficient, and that the results of simulat ions carried out using the method are in excellent agreement with the theory.