Lattice Boltzmann analysis of effect of heating location and Rayleigh number on natural convection in partially heated open ended cavity

Abstract

Natural convection characteristics of a partially heated open ended square cavity have been investigated numerically by using an in-house computational flow solver based on the passive scalar thermal lattice Boltzmann method (PS-TLBM) with D2Q9 (two-dimensional and nine-velocity link) lattice model. The partial part of left wall of the cavity is heated isothermally at either of the three different (bottom, middle and top) locations for the fixed heating length as half of characteristic length (H/2) while the right wall is open to the ambient conditions. The other parts of the cavity are thermally isolated. In particular, the influences of partial heating locations and Rayleigh number (10 3 ≤ Ra≤10 6 ) in the laminar zone on the local and global natural convection characteristics (such as streamline, vorticity and isotherm contours; centerline variations of velocity and temperature; and local and average Nusselt numbers) have been presented and discussed for the fixed value of the Prandtl number (Pr=0.71). The streamline patterns show qualitatively similar nature for all the three heating cases and Rayleigh numbers, except the change in the recirculation zone which is found to be largest for middle heating case. Isotherm patterns are shifted towards a partially heated wall on increasing Rayleigh number and/or shifting of heating location from bottom to top. Both the local and average Nusselt numbers, as anticipated, shown proportional increase with Rayleigh number. The cavity with middle heating location shown higher heat transfer rate than that for the top and bottom heating cases. Finally, the functional dependence of the average Nusselt number on flow governing parameters is also presented as a closure relationship for the best possible utilization in engineering practices and design.

Computational analysis of magneto-hydrodynamic natural convection in partially differentially heated cavity: Effect of cooler size

“…The details of the solution procedure and algorithm of the present in-house thermal lattice Boltzmann method can be found in our previous articles. 3,4…”

“…The grid test is conducted for extreme values of Hartmann and Rayleigh numbers. Five uniform lattice sizes (G 1 : 41 2 ; G 2 : 61 2 ; G 3 : 81 2 ; G 4 : 101 2 , G 5 : 121 2 ) are utilized for the purpose. Figure 2 shows the effect of different lattice nodes along the partially heated Nutrue¯ wall.…”

“…The effect of the change in the lattice size is found to be minimal on Nutrue¯ after G 3 . Therefore, keeping in mind the greater accuracy (or fewer truncation errors) in the numerical solution procedure, grid G 4 (101 × 101) is, however, found to be sufficiently refined enough to resolve the necessary hydrodynamics of MHD natural convection.

Figure 2.Grid independence study based on average Nusselt number (Nu) for partial heater and cooler size of H/2 for Ha = 0, 120 and Ra = 10 3 , 10 5 .

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“…of heat exchanger devices, solar heat collectors having insulated strips, micro-electronic devices, cooling systems of electronic devices, refrigerators and oven. 1–4 Such configurations have a simple geometry with the capability to explain a wide range of fluid mechanics and heat transfer phenomena. Therefore, it is a first choice for researchers for testing/validating new numerical solvers.…”

Effect of the aspect ratio of the shallow enclosure and built‐in rectangular blockage on MHD double‐diffusive free convection subjugated to non‐uniform boundary conditions

“…Therefore, an in-depth study of heat and mass transfer (HMT) characteristics in such systems subjected to nonuniform heating and concentration conditions is of prime essence. [11][12][13] The understanding of buoyancy-driven convection in an enclosed system is of prime significance due to the complex interaction between hydrodynamics and thermal and species transport parameters. As reported by Sathiyamoorthy et al, 12 the interaction and influence of the flow parameters on the boundary layers for the internal flows are highly complicated than the external ones.…”