Study of entropy decrease phenomenon in shock layer

Abstract

An entropy decrease phenomenon in the shock wave is studied. The statistical entropy of a unit mass system (UMS) is constructed based on statistical mechanics. Two terms in the microscopic statistical entropy are connected with the macroscopic entropy increment. In order to obtain the number density and velocity distribution function of argon gas, the direct simulation Monto Carlo method is adopted. The physical mechanism for entropy decrease phenomenon in the shock layer is revealed as compression work winning internal energy to produce the heat loss of a UMS.