Thermoacoustic instability leads to large vibrations and noise in a gas turbine engine. It is a common phenomenon in advanced gas turbine engines and has a potential to cause severe damage to gas turbine components. Therefore, it is required to predict and control thermoacoustic instabilities. The best and a simple way to understand the thermoacoustic instability is by simulating a Rijke tube. In this work, a CFD simulation has been carried out to generate and investigate the thermoacoustic instability in the Rijke tube. The frequency of oscillations of fluid properties and phase difference between them have been calculated. It has been observed that the results comply with the Rayleigh criteria. These results have been qualitatively compared with the published data and a good agreement was observed.