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In the present work, numerical simulations are performed to investigate the vortex shedding suppression phenomenon for mixed convective flows past a square cylinder in the large-scale heating regime. A full compressible flow model with variable transport and thermo-physical properties is employed to capture large-scale heating effects. The Reynolds number, Prandtl number, and Mach number are kept constant at Re = 100, Pr = 0.71, and M = 0.1, while the cylinder inclination (ϕ), free-stream inclination (α), and over-heat ratio (ϵ) are varied in the range [0, 45°], [0, 90°], and [0, 2], respectively. The governing equations are solved numerically using the particle velocity upwind (PVU-M+) scheme. The buoyancy parameter which governs the vortex shedding suppression process in the non-Boussinesq model is identified as RiNB=ϵFr222+ϵ, where Fr is the Froude number. Using the Stuart-Landau model, the neutral curves separating the steady and unsteady flow regimes are generated in the ϵ–ϕ and ϵ–α parametric spaces. The neutral curves show qualitatively similar characteristics as observed for Boussinesq models. The relative contribution of various large-scale heating effects in suppression of vortex shedding is also highlighted. This reveals that buoyancy effects followed by variations in transport properties play a major role in suppression of vortex shedding. The findings are also applicable to a range of low Re (O(100)) as supported by data obtained at Re = 130 for ϕ = 40°. The mechanism of vortex shedding suppression has been analyzed and extended for the large-scale heating scenarios.

In the present study, experimental studies have been performed to compare the thermal performance of two geometrically identical box-type solar (B-T-S) cookers. To carry out this aim, the thermal performance of BTS in terms of figure of merits, namely, first figure of merit (F1) and second figure of merit (F2) are calculated for both cooker as specified by the Bureau of Indian standards (BIS). At no load condition (i.e. stagnation test), it is found that first figure of merit for both cookers that is cooker 1, and cooker 2 is around 0.12. This implies that, both the cookers are identical in thermal performance. In addition to this, the effect of lugs height, reflectors numbers of pots and load on B-T-S cooker performance have also been investigated. From the results and discussion, it is concluded that the use of lugs reduced the heat transfer rate between cooking pot and absorber plate. Further it is found that the pot content temperature is enhanced by 25.5% and 23.4% by using mirror and aluminium reflector with cooker, respectively. While, it is observed that the performance parameters of B-T-S cooker in terms of F2 increases linearly with the increase of numbers of cooking pot (with correlation F2 = 0.0316n + 0.2238, where n is number of pots) and load (correlation as F2 = 0.0451m + 0.1844, where m is the mass of water in cooking pot) on the pot.

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The present work aims to numerically investigate the upward flow of air past an inclined square cylinder with an incidence angle equal to 45 o in the mixed convection regime at a fixed Reynolds number Re = 100. The governing equations are modelled by considering Boussinesq approximation. The critical Richardson number (Ric) for the suppression of vortex shedding (VS) is determined. By observing the instantaneous streamline patterns and the coefficient of lift plot with time near the critical value, it is found that VS suppression occurs at Ric = 0.78. Also, the aerodynamic characteristics such as lift and drag coefficient, the heat transfer characteristic, and the Strouhal number are studied by varying Ri in the range of [0.2, 1]. The role of thermal buoyancy on the aerodynamic parameters such as drag and lift coefficients, Nusselt number and Strouhal number are also studied in the mixed convection regime. It is found that mean drag coefficient and Nusselt number increases with the increase in Ri, and no lift is developed for any Ri, while the Strouhal number increases with increase in Ri and vanishes at a critical Richardson number. Further, the effect of thermal buoyancy on streamlines, isotherms and iso-vorticity contours are also presented.