Double diffusive mixed convection study in a vertical annulus at different aspect ratio and Richardson number

The present study has been considered in heat, mass transfer and the reversal flow occurrence inside the annulus of concentric vertical cylinders numerically. Both the thermal buoyancy and the buoyancy due to different concentrations are of equal magnitude and direction. The forced flow direction effect is investigated. The problem is considered a laminar flow and steady state. The influencing parameters are identified for the problem are Richardson number, Lewis number, and length to gap ratio and Radius ratio. The dimensionless gap is kept constant at unity. The Richardson number is varied from 0.1 to 10, dimensionless length from 5 to 25, the dimensionless radius ratio from 1.5 to 11 and the lewis number from 0.1 to 10. The dimensionless temperature and concentration distributions are illustrated at various range of parameters. In addition, the average values concerning Nusselt as well as Sherwood numbers are correlated. The reverse flow is examined at both aiding and opposing flows. The reverse flow existence is affected by the Richardson number and the length to gap ratio. The value concerning thermal Grashof number is stable at 104. Keywords: Double diffusion, Reverse flow, Vertical cylinder, Annulus ga