To numerically simulate the viscous interaction of a planar shock wave with a thermal layer, the ideal of numerical viscosity was adopted. The numerical viscosity is inherent in the finite difference equations of inviscid gas motion. A comparison of the flowfield structure between two calculations, one with and one without viscosity, is shown. Although there is a slight difference between the times of these two calculations, it is evident that the structure of the interaction is much larger when the flow is assumed to be inviscid. Although for the inviscid case, triple-point height λ is about 5.7 cm at τ = 11.100 (t = 377.4 μs), it is only about 4.25 cm at a slightly later time τ = 11.533 (t = 392 μs) when the viscous effects are accounted. This is because viscous effects can be thought of as a mechanism that introduces suction into the flowfield along the wall.