Three‐dimensional simulation of thermals using a split‐operator scheme

A three‐dimensional numerical model is developed to study the motion and mixing process induced by thermals. The model utilizes a split‐operator approach for the solution of the hydrodynamic equations and the advective diffusion equation. A conservative characteristics based scheme with flux‐limiter is employed to accurately approximate the advective terms in all equations and to prevent the generation of over and under shoots in the solution. In modelling the turbulent stresses and diffusion, the mixing length model is used. Cases of unit thermals in uniform or stratified ambient fluid and advected line thermals are simulated and the results verify the empirical equations for thermal parameters obtained from the reported experimental data.