Characterization of fluid flow patterns and heat transfer in horizontal channel mixed convection

Harmonic mechanical excitations of steady convective instabilities: A means to get more uniform heat transfers in mixed convection flows?

“…In Fig. 20(a) (18) It is independent on A exc like Eq. (17) This has already been analyzed in [10] and is confirmed here: when Dθ increases, the mixing of the flow in the channel core increases and its time averaged temperature is more uniform resulting in slightly smaller mean temperature gradients at walls (see [10] for more details).…”

“…Carrière and Monkewitz (1999) [16] showed that this pattern is a convective instability of the basic conductive Poiseuille flow. Mergui et al (2011) [17] and Benderradji et al (2008) [18] demonstrated that these rolls are triggered in real channels of finite transverse aspect ratio just downstream the leading edge of the heated plate and near the vertical walls due to the presence of velocity and temperature boundary layers adjacent to these walls. Ra // *=1728.83, B=10 [19] Ra osc *, B→∞ [8] Ra ≈ *, B→∞ [8] Ra ≈ *, B=10 [10] [8,10,19].…”

Effect of secondary flows due to buoyancy and contraction on heat transfer in a two-section plate-fin heat sink

“…A non-uniform hexahedral grid was employed along the flow direction for the discretization of the computational domain, as the grid was locally refined in the vicinity of the flow contraction, in order to fully capture the distinct flow features in that region. On the other hand, transversely to the flow direction the computational domain was discretized using equal hexahedral elements, as uniform grid density is required in order to resolve buoyancy induced secondary-flow patterns [15,25].…”

A 3D Low Mach Number model for high performance computations in natural or mixed convection newtonian liquid flows

“…The control parameters of this mixed convection water flow are the Reynolds number (Re = ρ 0ū0 h/µ 0 = 50, with ρ 0 = ρ(x = 0),ū 0 = u(x = 0) and µ 0 = µ(x = 0)), the Rayleigh number (Ra = 1.5 10 4 , built on the imposed heat flux) and the water Prandtl number (P r = 6.9 at 25 • C). Based on mesh sensitivity analysis previously made in a comparable configuration [14] the computational domain is made up with 750x200x20 H27 hexahedral finite elements uniformly distributed in the streamwise, spanwise and vertical directions. This mesh is built on 24 677 941 velocity and temperature nodes, and 3 169 971 pressure nodes.…”

“…We have also adapted the resulting projection algorithm to account for open boundary conditions, in order to deal with the two supplementary internal variables related to the Low Mach Number approximation, namely the thermodynamic pressure and its temporal derivative. In order to compare their respective capabilities both classical Boussinesq's approximation and the proposed LMN model have been used to compute a mixed convection water flow in a horizontal channel uniformly heated from below at prescribed heat flux (Re = 50, Ri = 3) in a configuration similar to that previously studied with the former model in [14].…”