Evolution equations for the decomposed components of displacement speed in a reactive scalar field
Journal article, 2021
simple decomposition of Sd into contributions due to (i) curvature, (ii) normal diffusion and (iii) chemical reaction, this work aims at deriving and exploring new evolution equations for these three contributions averaged over the reaction surface. Together with a previously obtained Sd-evolution equation, the three new equations are presented in a form that emphasizes the decomposition of Sd into three terms. This set of equations is also supplemented with a curvature-evolution equation, hence providing a new perspective to link the flame topology and its propagation characteristics. Using two direct numerical simulation databases obtained from constant-density and variable-density reaction waves, all the derived equations and the term-wise decomposition relations are demonstrated to hold numerically. Comparison of the simulated results indicates that the thermal expansion weakly affects the key terms in the considered evolution equations. Thermal expansion can cause variations in the averaged Sd and its decomposed parts through multiple routes more than introducing a dilatation term. The flow plays a major role to influence the key terms in all equations except the curvature one, due to a cancellation between negatively and positively curved surface elements.
turbulent reacting flows
Chalmers, Mechanics and Maritime Sciences, Combustion and Propulsion Systems, Combustions and Sprays
Journal of Fluid Mechanics
0022-1120 (ISSN) 1469-7645 (eISSN)Vol. 911 A38
Fluid Mechanics and Acoustics