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In this paper the effects of Diffusion thermo, radiation absorption and chemical reaction on MHD free convective heat and mass transfer flow of a nanofluid bounded by a semi-infinite flat plate are analyzed. The plate is moved with a constant velocity U0, temperature and the concentration are assumed to be fluctuating with time harmonically from a constant mean at the plate. The analytical solutions of the boundary layer equations are assumed of oscillatory type and are solved by using the small perturbation technique. Two types of nanofluids namely Cu-water nanofluid and TiO2-water nanofluid are used. The effects of various fluid flow parameters are discussed through graphs and tables. It is observed that the diffusion thermo parameter/radiation absorption parameter enhance the velocity, temperature and skin friction. This enhancement is very significant for copper nanoparticles. This is due to the high conductivity of the solid particles of Cu than those of TiO2. Also it is noticed that the solutal boundary layer thickness decreases with an increase in chemical reaction parameter. It is because chemical molecular diffusivity reduces for higher values of Kr. Keywords: MHD, Chemical reaction, Dufour effect, Nanofluid, Porous medium

Investigation of entropy generation assures significantly the trustworthiness of mechanical and electronic components. Entropy generation is useful in many applications including heat exchangers, capacitors, circuit boards and resistors. In this article, we discussed the optimization of entropy generation on a radiative MHD fluid flow combined with CCHF model in two instances i.e., hybrid nanofluid(PEG − Water + ZrO2 + MgO)and mono- nanofluid(PEG − Water + ZrO2)amidst (two) revolving disks with chemical reaction. Mathematical model describing the fluid flow is resolved by using a shooting procedure together with R-K 4th order method after converting as a system of ODEs. Outcomes are displayed via plots and impacts of the pertinent parameters on physical quantities such as heat transfer rate are elucidated using a statistical tool, correlation coefficient in two cases. Primary conclusions of this study are larger stretching parameter of the lower disk ameliorates axial velocity, volumetric nanoparticle parameter alleviates radial velocity, higher thermal relaxation parameter belittles the fluid temperature, radiation and rotation parameters improve the entropy generation in the fluid flow and concentration diminishes with larger chemical reaction parameter. Further, we observed that elongating parameters of both disks are having significant positive association with surface drag force near the disks in both occasions. However, there is a significant negative association between the heat transfer rates. Rotation parameters improves the entropy generation in the fluid flow. Validation of the current study is done by comparing the present findings with the available outcomes in the literature and found an adequate agreement.

An analytical solution of MHD free convective, dissipative boundary layer flow past a vertical porous surface in the presence of thermal radiation, chemical reaction and constant suction, under the influence of uniform magnetic field which is applied normal to the surface is studied. The governing equations are solved analytically using a regular perturbation technique. The expressions for velocity, temperature and concentration fields are obtained. With the aid of these, the expressions for the coefficient of skin friction, the rate of heat transfer in the form of Nusselt number and the rate of mass transfer in the form of Sherwood number are derived. Finally the effects of various physical parameters of the flow quantities are studied with the help of graphs and tables. It is observed that the velocity and concentration increase during a generative reaction and decrease in a destructive reaction. The same observed to be true for the behavior of the fluid temperature. The presence of magnetic field and radiation diminishes the velocity and also the temperature.