  We argue that it is currently impossible to simulate X-ray clusters using
correct equations, because even the MHD description is not applicable. But
since fluid simulations actually reproduce observations quite well, one may try
to improve the fluid codes by including molecular transport of heat and
momentum. We calculate the effective molecular viscosity for the simplest model
of magnetic field and obtain 1/5 of the Braginskii value, similar to 1/3 of
Spitzer for the heat conduction. This is large enough to noticeably damp the
X-ray cluster turbulence.
