Mohammad Mamun

Analysis of magnetohydrodynamic mixed convection and joule heating in lid-driven cavity having a square block

A numerical analysis is conducted to understand the effect of magnetic field and joule heating on the flow and thermal fields in a lid-driven cavity with a centered heat-conducting horizontal square block. The two sidewalls are maintained at uniform but different temperatures Th and Tc (Th  > Tc ), while the horizontal top and bottom walls are adiabatic. The left vertical wall moves up in the y-direction at a constant speed, while the other walls remain stationary. An electrically conducting fluid is considered within the cavity. The physical problem is first represented mathematically by different sets of governing equations along with boundary conditions. A Galerkin weighted residual finite element method with a Newton–Raphson iterative algorithm is adopted to solve the governing equations along with the boundary conditions. The computation is carried out for wide ranges of Richardson numbers, magnetic parameter, joule heating parameter, and the size of the inner block. Results are presented in the form of streamlines, isothermal lines, average Nusselt number at the hot wall, and average fluid temperature in the cavity for the mentioned parameters. It is found that the flow field and temperature distribution strongly depend on magnetic parameter, joule heating parameter, and the size of the inner block at the pure mixed convection region.

Combined effect of Reynolds and Grashof numbers on mixed convection in a lid-driven T-shaped cavity filled with water-Al2O3 nanofluid

Lid-driven mixed convection has been given immense importance due to its wide range of applications. A T-shaped cavity is introduced and pertinent parameters controlling mixed convection phenomenon are analyzed in this paper. Water-Al2O3 nanofluid is considered inside the cavity to augment heat transfer rate. Galerkin weighted residual method of finite element analysis is applied for the numerical simulations. Numerical solution is obtained for different solid volume fractions of nanofluid (φ=0−0.15)φ, Grashof numbers (Gr=0.15000)Gr− and Reynolds numbers (Re=0.311000)Re− in laminar flow regime. Special attention is given on the analysis of flow at the pure mixed convection regime. It is found that Grashof, Reynolds and Richardson numbers along with solid volume fraction of nanofluid have significant effect on heat transfer characteristics inside the cavity. Results are presented using streamline and isotherm contours along with related variation of average Nusselt numbers of the heated wall and average fluid temperature inside the cavity.

Analysis of Mixed Convection in a Lid Driven Trapezoidal Cavity

Convection is the heat transfer mechanism affected by the flow of fluids. The amount of energy and matter are conveyed by the fluid can be predicted through the convective heat transfer. The convective heat transfer splits into two branches; the natural convection and the forced convection. Forced convection regards the heat transport by induced fluid motion which is forced to happen. This induced flow needs consistent mechanical power. But natural convection differs from the forced convection through the fluid flow driving force which happens naturally. The flows are driven by the buoyancy effect due to the presence of density gradient and gravitational field. As the temperature distribution in the natural convection depends on the intensity of the fluid currents which is dependent on the temperature potential itself, the qualitative and quantitative analysis of natural convection heat transfer is very difficult. Numerical investigation instead of theoretical analysis is more needed in this field. Two types of natural convection heat transfer phenomena can be observed in the nature. One is that external free convection that is caused by the heat transfer interaction between a single wall and a very large fluid reservoir adjacent to the wall. Another is that internal free convection which befalls within an enclosure. Mathematically, the tendency of a particular

Numerical study of two and three bladed Savonius wind turbine

The aim of this paper is to compare aerodynamic characteristics of two and three bladed Savonius rotor with different overlap ratios by numerical analysis. The models with 0%, 20%, and 30% overlap having the same blade diameter and height are used for the comparison. To ensure the simulation model was correct the results obtained from the CFD were compared with experimental results. The established simulation model was used to find the static torque coefficients and power coefficients to analyze the aerodynamic performance of the taken geometries. From the analysis it was found that rotor with less blade number produces higher torque. It was also found that the rotors with no overlap produces negative torque and the introduction of overlaps in the rotor eliminates the negative torque. Another finding from the analysis is the increase in Reynolds number increases the static torque in the rotor.