Numerical investigation and reduced order model of mixed convection at a backward facing step with a rotating cylinder subjected to nanofluid

• Mixed convection at a BFS flow with a rotating cylinder is studied.
• Averaged Nu increases with nano-particle volume fraction.
• Flow and thermal patterns behind the step are changed due to cylinder rotation.
• POD based ROM of the system is obtained for a range of parameters.

In the present study, numerical investigation of mixed convection at a backward facing step with a rotating cylinder subjected to nanofluid is conducted and a reduced order model of the system is obtained by using the proper orthogonal decomposition method. The governing equations are solved with a finite element based commercial solver. The effects of various pertinent parameters, Reynolds number, cylinder angular velocity and nanofluid volume fraction on the fluid flow and heat transfer characteristics are numerically studied. It is observed that flow field and thermal patterns change for different parameters and heat transfer enhancement is obtained for some combinations of parameters. Length averaged Nusselt number plots indicate that there is almost a linear increase in the heat transfer enhancement with increasing Reynolds number and nanoparticle volume fraction. Heat transfer enhancement is obtained for cylinder angular velocities of Ω=-4.5Ω=-4.5 and Ω=1.5Ω=1.5. A reduced order model of the system with proper orthogonal decomposition method is obtained and it provides accurate results when compared to high fidelity CFD model of the system.