Investigation of Transition to Turbulence in Compressible Natural Convection Flow along a Vertical Heated Plate using Direct Numerical Simulation*

The report focuses on the flow dynamics involved in transitional phenomena generated under the sole action of buoyancy forces for a spatially developing compressible turbulent natural convection flow for air along a vertical flat surface heated with uniform heat flux using direct numerical simulation. No external perturbations are imposed on the flow field to generate transition to turbulence. Mean velocity and temperature profile distribution across boundary layer along with growth of corresponding boundary layer are measured. Velocity transition immediately follows thermal transition. Velocity and temperature fluctuations across the boundary layer are measured. Predominant frequencies of the disturbances are determined through FFT analysis. Beginning of transition happens around 157 W/m and end of transition at 226 W/m. Visualization of instantaneous flow field performed shows a very natural transition to turbulent.