Smoothed particle hydrodynamics (SPH) is an effective numerical method
to solve various problems, especially in astrophysics, but its applic
ations have been limited to inviscid flows since it is considered not
to yield ready solutions to fluid equations with second-order derivati
ves. Here we present a new SPH method that can be used to solve the Na
vier-Stokes equations for constant viscosity. The method is applied to
two-dimensional Poiseuille flow, three-dimensional Hagen Poiseuille f
low and two-dimensional isothermal flows around a cylinder. In the for
mer two cases, the temperature of fluid is assumed to be linearly depe
ndent on a coordinate variable x along the flow direction. The numeric
al results agree well with analytic solutions, and we obtain nearly un
iform density distributions and the expected parabolic and paraboloid
velocity profiles. The density and velocity field in the latter case a
re compared with the results obtained using a finite difference method
. Both methods give similar results for Reynolds number R(e)=6, 10, 20
, 30 and 55, and the differences in the total drag coefficients are ab
out 2 similar to 4%. Our numerical simulations indicate that SPH is al
so an effective numerical method for calculation of viscous flows.