A pressure wave refrigerator is an unsteady flow device which can transfer energy by pressure wave from one fluid to the other. Construction wise it has one or a set of inlet port and one or a set of receiving tubes. Hot high pressure gas enters the receiving tube through inlet port and compresses the existing low pressure gas inside the tube through a shock wave. While the shock wave moves forward, an expansion wave moves in the reverse direction and cools the gas at the inlet end of the receiving tube. This gas is further expanded and cooled when the tube is connected to the exhaust port of the rotor. The gas with shock wave dissipates thermal energy through the tube wall into the environment. In this paper a two dimensional axisymmetric CFD model is presentedto understand wave interactions in an oscillating flowinside a receiving tube. Numericalinvestigations were carried outunder varying inlet pressureand length of the receiving tube. Effects of a shock absorber at the closed end of the tube for minimizing the reflected shock wave were also studied. Isentropic efficiencies for various cases are computed and comparatively presented in the paper.