Numerical study of flow physics in supersonic base-flow with mass bleed

Abstract

Large Eddy Simulation (LES) with dynamic sub-grid scale eddy viscosity model has been applied to numerically investigate the evolution of complicated flow structures in supersonic base flow with mass bleed. Mean flow properties obtained from numerical simulations, such as axial velocity, pressure on the base surface, have been compared with the experimental measurements to show that LES is able to predict the mean flow properties with acceptable accuracy. The data obtained from LES has been further analyzed to understand the evolution of coherent structures in the flow field. Periodical shedding of vortical structures from the outer shear layer has been observed and it has also been found that this vortex shedding is associated with the flapping of the outer shear layer. The frequency of flapping of the outer shear layer has been found out and the phase-averaged streamlines have been analyzed to further study the evolution of vortical structures associated with this flapping. The phase-averaged streamline plots clearly elucidate the evolution of vortical structures along the outer shear layer. Further, the study of these structures is investigated by performing Proper Orthogonal Decomposition (POD) analysis of the data, obtained along the central plane in the wake region. The POD results also 2 seem to agree well with the observations made in the phase averaged streamline plots, as the concentrated energy and enstropy are observed in the outer shear layer with fewer POD modes.

Effect of grid sensitivity on the performance of wall adapting SGS models for LES of swirling and separating–reattaching flows

“…The temporal terms use an implicit second order discretization. The solver had been extensively used for a large number of studies including both reacting and non-reacting flows [16,17,18,19,20,21,22].…”

Numerical study of trailing and leading vortex dynamics in a forced jet with coflow

“…The fluctuation kinetic energy forms an auto-covariance matrix, calculated from the fluctuating component of the instantaneous velocity. One can refer to the published literature [24][25][26][27][28] for the formulation and further details related to the POD. Further, for variable density (in turn temperature) flows, both fluctuating velocity and temperature fields are taken into consideration, while the solution of POD energy matrix (a combination of kinetic energy and thermal energy [29][30][31]) provides the eigenvalue of the system.…”

Investigation of mixing characteristics in strut injectors using modal decomposition

“…Mathematically, POD attempts to search for set of orthonormal basis vectors in a lower dimension by decomposing ensemble of realizations while minimizing the error between the original data and its 6 projection onto the lower dimensional space. The mathematical description of this decomposition technique can be found in literature [18][19][20] as briefly described here.…”

“…where ' ̅ 'denotes averaging over time. Further details regarding the computation of POD modes and reconstruction can be found in the published literature [18][19][20][21][22] .…”