Direct numerical simulation of MHD heat transfer in high Reynolds number turbulent channel flows for Prandtl number of 25

Modeling of MHD turbulent heat transfer in channel flows imposed wall-normal magnetic fields under the various Prandtl number fluids

“…magnetic field [10,11]. In the DNS database, constant temperatures at the top and bottom boundaries ( top >  bed ;  top : top wall temperature and  bed : bottom wall temperature) were imposed under the assumption of a passive scalar field.…”

“…The numerical conditions of the DNS database are shown in Table 1, where the superscript + denotes the nondimensional quantities normalized by friction velocity (u ) and kinematic viscosity (). In the computations, the thermal properties of FLiBe were used [11], the friction Reynolds number (Re = u h/ ) was kept constant at 400, the molecular Prandtl number (Pr = /˛, ˛: thermal diffusivity) was set to 25 (FLiBe), and the Hartman number (Ha = B 0 2h( / ) 1/2 , B 0 : wall-normal magnetic field, : electrical conductivity, and : density) was changed from 0 to 28. In the DNS database, the bulk Reynolds numbers (Re b = U b 2 h/ , U b : bulk velocity) were approximately 14,000.…”

“…To investigate the effects of the molecular Prandtl number, the DNS database [10] for KOH solution (Pr = 5.25) and lithium (Pr = 0.025) under the same Re and Ha conditions [11] were also used. The KOH solution was used as the FLiBe simulant fluid, as described by Takeuchi et al [13].…”

“…Using the turbulent eddy viscosity, the governing equations for mean velocity and temperature in a fully developed turbulent channel flow imposed on a wall-normal constant magnetic field [10,11], are described as follows:…”

“…In this study, we discuss heat transfer modeling under the MHD effects by means of the DNS database [10,11]. In this DNS database, equivalent conditions [12,13], such as Reynolds number, Hartmann number, and molecular Prandtl number are selected.…”