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This investigation examines the role of pressure in the stability of planar, quadratic flows and its subsequent modeling vis- à-vis the second moment closure recourse to turbulence. In the first section, we isolate and analyze the effect of pressure action in the (linear) stability of different regimes of quadratic flows. Pressure effects can be diametric contingent upon the flow regime, wherein for hyperbolic flows, pressure supresses the flow instability, whereas for elliptic flows, pressure engenders and sustains the elliptic flow instability. At the transition between these regimes, for purely sheared flows, pressure does not alter the nature of flow stability. These observations are explicated, from a physics and a mathematical perspective. Thence, we address the question of whether single point closures can replicate the action of pressure and if so, to what extent. Each feature of the dynamics of pressure action is examined, systematically and comprehensively, in regard to its amenability to single-point closure modeling. Based on this analysis, we introduce studied compromises in the compass of modeling objectives and allowances in the modeling framework to arrive at a “best-possible" model. Thereupon, the predictions of said model are compared to DNS and experimental results; and contrasted against popular models to exhibit the efficiency of this approach.
Author(s):
Aashwin Mishra
Aerospace Engineering Department, Texas A&M University, College Station, Texas
United States
Sharath Girimaji
Aerospace Engineering Department, Texas A&M University, College Station, Texas
United States