Analysis of reattachment length dynamics in cavities

Autor: Paulius Vilkinis, Nerijus Pedišius
Rok vydání: 2020
Předmět:
Zdroj: Experimental Thermal and Fluid Science. 119:110211
ISSN: 0894-1777
DOI: 10.1016/j.expthermflusci.2020.110211
Popis: Recirculation zone dynamics in a cavity located in the bottom wall of a water channel with height h = 0.3 mm and width b = 0.9 mm are investigated experimentally and numerically. A microparticle image velocimetry method and instrumentation are used for the experimental determination of flow velocity distribution and reattachment pattern with Reynolds number from ReDh = 30–2000, cavity length to depth ratios of L/h1 = 10 and 16, and channel expansion ratios of H/h = 1.3, 1.5, 2, 3, and 5. Numerical simulation using commercially available Ansys Fluent software is conducted for analysis of the influence of flow regime and cavity dimensions by changing ReDh, L/h1, and H/h in the ranges of (1–105), (8–36) and (1.25–5), respectively. The experimental and numerical simulation results show that in a laminar flow regime reattachment length increases with increasing ReDh in the same manner as in flow over a backward-facing step. Reh1 and H/h are the main scaling parameters for the reattachment length. However, the results suggest that the transition to a turbulent flow regime occurs earlier due to the small channel spanwise aspect ratio AR = b/h = 3. Reh1 ≈ 500 and Reh1 ≈ 2000 are the critical values that determine the onset of flow transition from a laminar to a turbulent regime and the onset of fully developed turbulent flow, respectively. In addition, it is found that the influence degree of channel expansion ratio depends on whether H/h > 2 or H/h
Databáze: OpenAIRE
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