Dependence on the initial conditions of scalar mixing in the turbulent wake of a circular cylinder

作者：Beaulac S^*; Mydlarski L

来源：Physics of Fluids, 2004, 16(8): 3161-3172.

DOI：10.1063/1.1766033

The effect of the initial conditions on scalar mixing in the turbulent wake of a circular cylinder is studied. The scalar under consideration is temperature and it is injected by means of an array of parallel, heated, fine wires (a mandoline). The initial length scale of the velocity field is varied (relative to that of the scalar field) by changing the downstream location of the mandoline. The initial length scale of the scalar field is modified by changing the number of mandoline wires and their spacing. In accordance with previous results in homogeneous, isotropic, grid turbulence, increasing the initial length scale of the velocity field was found to (i) increase the decay rate of scalar variance (m), (ii) decrease the integral scale of the scalar field (l(theta)), and (iii) increase the mechanical to thermal time scale ratio r. Varying the mandoline wire spacing had little effect on m, l(theta), or r. Increasing the width of the mandoline decreased the scalar variance decay rate. Doing so, however, had negligible effect on the structure of the scalar field (i.e., l(theta) or r). The independence of the scalar variance decay rate and the structure of the scalar field-the opposite of what is observed in grid turbulence-is attributed to the inhomogeneous nature of the flow.

• 出版日期2004-8