Supercritical heat transfer characteristics of couple stress convection flow from a vertical cylinder using an equation of state approach

Abstract

The present work describes numerical simulations of the supercritical heat transfer characteristics of couple stress fluid flow from a vertical cylinder using the equation of state approach. Redlich-Kwong (RK-EOS) and Van der Waals (VW-EOS) equations of state (EOS) are deployed to derive the equation for the thermal expansion coefficient (β). The β values calculated based on RK-EOS are sufficiently close to the experimental values when compared with those based on VW-EOS. Due to the presence of couple stresses in the fluid, highly nonlinear coupled partial differential equations are generated. These primitive equations are reduced to dimensionless form by using suitable non-dimensional quantities. An unconditionally stable finite difference technique is used to solve the normalized conservation equations under physically viable boundary conditions, in order to describe the natural convection heat transfer characteristics of couple stress fluid external to a vertical cylinder in the supercritical region. For different values of the emerging physical parameters, numerical data for couple stress fluid for the case of Nitrogen is generated and presented in the form of graphs and tables. The present computations indicate that the velocity field is suppressed close to the cylinder whereas it is enhanced away from the cylinder with increasing values of reduced temperature in the supercritical fluid region. The reverse behavior is observed for reduced pressure. The present results are compared with the previous results and found to be in good agreement. Applications of the model include super-critical coating dynamics in the aerospace and medical industries.