Abstract:Buoyancy driven convection in a square cavity induced by two mutually orthogonal arbitrarily placed heated thin plates is studied numerically under isothermal and isoflux boundary conditions. The flow is assumed to be two-dimensional. The coupled governing equations were solved by the finite difference method using the Alternating Direction Implicit technique and Successive Over Relaxation method. The steady state results are depicted in terms of streamline and isotherm plots. It is found that the resulting co… Show more
“…The values of the Nusselt number corresponding to all these situations can be found in Table III (where it is shown that the intensity of heat exchange between the surface of the step and the fluid increases as the Rayleigh number becomes higher). Interestingly, the set of values reported there also indicates that the mechanism of the Hadley type (being operative near the vertical side of the step) is much more efficient in transporting heat than that due to a heating-from-below condition at work along the horizontal side of the step (this finding being in line with other studies where square cavities with a heated plate built in vertically or horizontally or with a finned heated plate were considered, see, e.g., Oztop et al [58]; Saravanana et al [59]; Saravanan and Sivaraj [60]; Nadjib et al [61]; we will come back to this concept in Sect. 3.1.3).…”
Section: Patterning Behavior For the Cavity With Adiabatic Floorsupporting
The flow over a topography or a step is a fundamental problem in fluid dynamics with relevance to many fields and circumstances. In the present analysis direct numerical simulation (DNS) is used to examine the properties of the thermofluid-dynamic field in a square cavity with a heated obstruction located on the bottom. The involved dynamics include forced flow driven by injection of cold fluid through an orifice and the buoyancy convection of thermal origin, which naturally emerges in the considered cavity as a result of the prevailing temperature gradients. The relative importance of these mechanisms is assessed by considering different values of the Rayleigh number (spanning several orders of magnitude) and using a peculiar analysis hierarchy where selected effects are intentionally switched on or off depending on the targeted regime. In particular, first, attention is paid to pure thermogravitational convection driven by the presence of vertical and horizontal heated surfaces (the hot sides of the obstruction); then, the hybrid regime is examined where buoyancy convection is modulated by currents of forced flow for values of the Richardson number 1. We also explore the resulting patterning behavior for different thermal and kinematic boundary conditions (distinct thermal behaviors of the top wall and alternate positions of the inflow and outflow sections). For each case, the Nusselt number relating to the vertical and horizontal sides of the obstruction is evaluated and put in relation with the flow topology. The study is also supported by analysis of the frequency spectrum for the situations in which relatively chaotic states emerge.
“…The values of the Nusselt number corresponding to all these situations can be found in Table III (where it is shown that the intensity of heat exchange between the surface of the step and the fluid increases as the Rayleigh number becomes higher). Interestingly, the set of values reported there also indicates that the mechanism of the Hadley type (being operative near the vertical side of the step) is much more efficient in transporting heat than that due to a heating-from-below condition at work along the horizontal side of the step (this finding being in line with other studies where square cavities with a heated plate built in vertically or horizontally or with a finned heated plate were considered, see, e.g., Oztop et al [58]; Saravanana et al [59]; Saravanan and Sivaraj [60]; Nadjib et al [61]; we will come back to this concept in Sect. 3.1.3).…”
Section: Patterning Behavior For the Cavity With Adiabatic Floorsupporting
The flow over a topography or a step is a fundamental problem in fluid dynamics with relevance to many fields and circumstances. In the present analysis direct numerical simulation (DNS) is used to examine the properties of the thermofluid-dynamic field in a square cavity with a heated obstruction located on the bottom. The involved dynamics include forced flow driven by injection of cold fluid through an orifice and the buoyancy convection of thermal origin, which naturally emerges in the considered cavity as a result of the prevailing temperature gradients. The relative importance of these mechanisms is assessed by considering different values of the Rayleigh number (spanning several orders of magnitude) and using a peculiar analysis hierarchy where selected effects are intentionally switched on or off depending on the targeted regime. In particular, first, attention is paid to pure thermogravitational convection driven by the presence of vertical and horizontal heated surfaces (the hot sides of the obstruction); then, the hybrid regime is examined where buoyancy convection is modulated by currents of forced flow for values of the Richardson number 1. We also explore the resulting patterning behavior for different thermal and kinematic boundary conditions (distinct thermal behaviors of the top wall and alternate positions of the inflow and outflow sections). For each case, the Nusselt number relating to the vertical and horizontal sides of the obstruction is evaluated and put in relation with the flow topology. The study is also supported by analysis of the frequency spectrum for the situations in which relatively chaotic states emerge.
“…Unlike in [24,25] we have plate-plate and plate-wall temperature ratios. We introduce them through the non-dimensional temperature ratios…”
Section: Problem Formulation and Solution Proceduresmentioning
confidence: 87%
“…The grids 101 × 101 and 121 × 121 gave almost identical results. Hence considering both the accuracy and the computational time, the computations were all performed with a 101 × 101 grid and further details including validation of the code developed and grid independency study can be seen in our earlier works [24,25].…”
Section: Problem Formulation and Solution Proceduresmentioning
confidence: 99%
“…Papanicolaou and Jaluria [22] and Icoz and Jaluria [23] have considered such configuration in their design and optimization of cooling systems for electronic equipments. Natural convection in a square cavity induced by two mutually perpendicular heated plates were studied by the authors [24,25]. Mixed convection in a lid-driven enclosure filled with a nanofluid and induced by two mutually orthogonal thin plates have been investigated by Wang et al [26].…”
“…Kakarantzas et al [11] used a direct numerical method with a fractional semi-implicit scheme approach to simulate natural hydromgnetic convection in a vertical cylindrical cavity with sinusoidal top wall temperature variation. Saravanan et al [12] examined numerically the two-dimensional buoyancy-driven convection in a square cavity with isoflux and isothermal boundary conditions. Walker and Homsy [13] investigated buoyancy-driven convection in a porous cavity.…”
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