( A g ? F e 3 O 4 / H 2 O ) hybrid nanofluid Aspen® BEM CANDU-6 CFD Colebrook equation Colebrook-White Computational Fluid Dynamics (CFD) simulation OpenFOAM PHWR POD Padé polynomials Positive Temperature Coefficient (PTC) elements SPIV T-section prism X-ray microtomography acoustic streaming actuator disc air heater axial piston pumps boundary layer bubble generation bubble size capture efficiency centrifugal pump chemical reaction computational burden computational fluid dynamics concentration condensation