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It observers that an object is submerged in a liquid, more pressure is applied to its bottom surface than its top surface, as a result pressure rises within depth of fluids. A buoyancy force is generated due to the pressure difference. In the current investigation, the mathematical formulation of bio-convective stagnation point flow of a radiative Maxwell fluid with multiple slip effect on an exponentially porous stretching surface is analyzed thoroughly. The buoyancy assisting and opposing conditions with magnetic field are discussed in the current investigation. Moreover, the energy and concertation equations are formulated by the utilization of Cattaneo–Christov theory and non-uniform heat source/sink. The flow model is developed in the form of partial derivatives, then use the similarity variables to convert the physical system into nonlinear ordinary derivative. The nonlinear system is tackled numerically with the help of Bvp4c approach on the MATLAB. The graphical upshots for various emerging parameter are observed with two aspects: buoyancy assisting λ > 0 and buoyancy opposing λ < 0 . The observation shows that the greater values of mixed convection parameter improves the fluid velocity for assisting flow λ > 0 , while declining trend is noticing for opposing flow situation λ > 0 . Further, it is worth noticing that stronger inputs of thermal and concentration relaxation parameter yield lesser thermal and concentration diffusivity, which reduces the temperature and nanoparticles concentration. [ABSTRACT FROM AUTHOR]

We investigate the influence of cross thermal buoyancy to initiate the vortex shedding process around two side-by-side circular cylinders kept in a free stream flow. The critical buoyancy parameter is assessed for the Reynolds number in the range 10–40. In the stated range, a steady separated flow evolves under the pure forced convective condition. However, with the introduction of thermal buoyancy, instability grows and at a specific value of the buoyancy parameter, the flow turns into unsteady periodic with the formation of vortex shedding. The above phenomena have been examined numerically by a two dimensional simulation based on a finite volume method for a fixed gap spacing between the cylinders and considering air as the working medium. It is observed that the strength of the buoyancy could be a decisive factor in demarcating various flow regimes. The critical strengths of buoyancy where the flow transforms into unsteady periodic from the steady pattern are estimated for the Reynolds number range. It shows a decreasing pattern with increasing Reynolds number. The flow transition is visualized through the vorticity, isotherm contours, lift signals and phase diagrams. Furthermore, a regime diagram is constructed to clearly depict various zones of hydrodynamic behavior. [ABSTRACT FROM AUTHOR]

Homotopic solutions for Jeffrey material in frames of buoyancy forces are constructed in this research. The improved Fourier-Fick laws are considered for formulation. In addition, variable liquid aspects (thermal conductivity, mass diffusivity) along with heat source are accounted. Prandtl's boundary-layer idea is utilized to model the problem. Involvement of similarity variables resulted into non-linear system of coupled equations. The well-known homotopic scheme is employed for non-linear analysis. Besides, a comprehensive discussion is reported for arising dimensionless variables vs. significant profiles. Our results indicate a rise in thermal and solutal fields when variable conductivity and mass diffusivity parameters are increased. [ABSTRACT FROM AUTHOR]

An experiment was performed in this study to investigate the effect of duct spanwise inclinations on the longitudinal vortex pattern in an air mixed convective flow. Key parameters, including Reynolds (Re) numbers from 20 to 30 and Grashof (Gr) numbers from 4071 to 10,855, are investigated. The spatial and temporal attributes of longitudinal vortex rolls (LVRs) are examined via flow field visualization and transient temperature measurement in details. Compared with the corresponding non-sloping case, the duct inclination significantly influences the LVR evolution. Due to the non-zero spanwise buoyancy, the vortex roll tends to be asymmetrical across the span and causes the delayed onset of lower LVRs. The temperature fluctuates significantly with time adjacent to the upper sidewall at the larger tilt angle. In an inclined duct, lower LVRs will stretch spanwise to squeeze upper vortex rolls with a decrease in Re number. Increasing the Gr number is beneficial to LVR formation for a smaller spanwise-inclined angle. However, the increase in either Gr number or tilt angle makes the vortex flow relatively unstable. We also provide an empirical expression to determine the vortex onset as a function of Re , Pr , Gr numbers, and the tilted angle. [ABSTRACT FROM AUTHOR]