Effect of surface roughness on gas flow in microchannels by molecular dynamics simulation

Combined Effects of Pipe Diameter, Reynolds Number and Wall Heat Flux and on Flow, Heat Transfer and Second-Law Characteristics of Laminar-Transitional Micro-Pipe Flows

“…These justifications are common in several recent numerical studies on roughness induced flow and heat transfer investigations, like those of Engin et al [8], Koo and Kleinstreuer [12] and Cao et al [20]. The flow boundary conditions are based on the facts that on the pipe wall no-slip condition and constant heat flux exist, and flow and thermal values are maximum at the centerline.…”

“…The present roughness model is based on the triangular structure of Cao et al [20] (Figure 1b), where the roughness amplitude is characterized by ε and period by ω. In all computations, the roughness periodicity parameter (ω' = ω/ε) is kept fixed to ω' = 2.31, which corresponds to the equilateral triangle structure (Cao et al [20]).…”

“…In all computations, the roughness periodicity parameter (ω' = ω/ε) is kept fixed to ω' = 2.31, which corresponds to the equilateral triangle structure (Cao et al [20]). Equation 1 numerically characterizes the model of Cao et al [20] with the implementation of the amplitude and period. The model function (f ε (z)) is repeated in the streamwise direction throughout the pipe length, where the Kronecker unit tensor (δ i ) attains the values of δ I = +1 and -1 for 0 ≤ z ≤ ε 2 2.31 and ε 2 2.31 ≤ z ≤ 2.31ε respectively.…”

“…In a complementary work, the role of fouling on entropy generation, as compared to that for clean surface tubes, was studied by Sahin et al [19]. Cao et al [20] employed non-equilibrium molecular dynamics simulation to investigate the effect of the surface roughness on slip flow of gaseous argon. More comprehensive research comprised both flow and heat transfer characteristics driven by roughness, such as Wu and Cheng [6], who reported on the Nusselt number augmentations with surface roughness, Kandlikar et al [10] findings on heat transfer manipulation due to roughness, Wen et al [11] work on the effects of the imposed wall heat flux, mass flux and strip inserts on heat transfer rates in small diameter tubes, Koo and Kleinstreuer's [12] evaluations on the temperature field with viscous dissipation, a review by Obot [16] indicating the variation of laminar Nusselt numbers with the square root of the Reynolds number and finally Ozalp's [21,22] numerical compressible flow investigations for aerospace propulsion applications.…”

Fluid Mechanics, Heat Transfer and Thermodynamic Issues of Micropipe Flows

“…1(b)) is characterized by the two denoting parameters of roughness amplitude (ε) and period (ω). The outline model is equilateral-triangular in nature (Cao et al, 2006), such that the roughness periodicity parameter (ω'=ω/ε) is kept fixed to ω'=2.31 throughout the study. The implementation of the amplitude and period are defined by Eq.…”