Uniform shear flow under thermally relativistic limit: Case of zero Lorentz contraction

The uniform shear flow (USF) under the thermally relativistic limit is discussed on the basis of Truesdell’s theory of the USF for the nonrelativistic gas, when the Lorentz contraction is negligible. We investigate the solution of the USF under the thermally relativistic limit using the pseudo Maxwellian molecule. Under the thermally relativistic limit, solutions of seven moment equations for the USF, which are obtained from Grad’s 14 moment equations by Israel–Stewart, violate the positivity of the pressure tensor, when the dimensionless truncation number is larger than the threshold value owing to the contribution of the dynamic pressure, whereas solutions of six moment equations for the USF never violate the positivity of the pressure tensor.