Pore-scale large eddy simulation of turbulent flow and heat transfer over porous media

Flow leakage and Kelvin–Helmholtz instability of turbulent flow over porous media

“…Additionally, in a composite porous-fluid system, recent experimental studies have demonstrated that, for specific blockage ratios and pore densities, the fluid in the porous region is pushed upward into the non-porous region at the porous-fluid interface before reaching the porous block end (flow leakage) [30,31]. Recently, the flow exchange and heat transfer between porous and non-porous regions in a composite porous-fluid system with Re=3600 are studied numerically by Jadidi et al [32], using pore-scale large eddy simulation (LES).…”

On the Mechanism of Turbulent Heat Transfer in Composite Porous-Fluid Systems with Finite Length Porous Blocks: Effect of Porosity and Reynolds Number

“…For the latter one, a sudden change in the turbulence statistics is detected near the porous-fluid interface [19,[23][24][25]29]. In contrast, for the former one (finite length porous block), the sudden change in the turbulence statistics occurs away from the interface [30,31]. This means that in the case of a finite porous block, the earlier findings in the literature [24,25,28,29,32] are not valid over the entire porous length.…”

“…Figure 4(b, d, f) demonstrates a forest of unorganised hairpin coherent structures for high-porosity cases. The pattern of hairpin structures corresponds to the arrangement of counter-rotating vortex pairs (CRVPs) above the interface [30,31]. Moreover, flow leakage quantification for high-and low-porosity cases (discussed in Figure 6) indicates that the flow leakage reduces drastically for high-porosity cases, which disorders the organised pattern of CRVPs.…”

“…Recently, Jadidi et al [30,31] utilized pore-scale large eddy simulation (LES) to investigate flow and heat transfer in a composite porous-fluid system with a finite-length porous block. The porous block's characteristics were as follows: 𝐵𝑅 = 0.5 (𝐵𝑅 is blockage ratio which is the ratio of the porous height to the channel height); 𝐴𝑅 = 3.3 (𝐴𝑅 is the aspect ratio defined as the ratio of the porous length to its height); 𝐿𝑅 = 10 (𝐿𝑅 is the length ratio defined as the ratio of porous length to the pore element diameter).…”

“…The porous block's characteristics were as follows: 𝐵𝑅 = 0.5 (𝐵𝑅 is blockage ratio which is the ratio of the porous height to the channel height); 𝐴𝑅 = 3.3 (𝐴𝑅 is the aspect ratio defined as the ratio of the porous length to its height); 𝐿𝑅 = 10 (𝐿𝑅 is the length ratio defined as the ratio of porous length to the pore element diameter). In contrast to fully-developed porous channel flows [24,25,28,29,32], Jadidi et al [30,31] showed a different pattern for the distribution of turbulent kinetic energy (TKE), turbulence production and consequently, turbulent heat flux above the interface due to the finite length of the porous block. They reported that the turbulent interactions between the porous and non-porous regions are mainly governed by the TSB and flow leakage.…”