An experimental and numerical study of the structure and stability of laminar opposed-jet flows

A Ciani, W Kreutner, CE Frouzakis, K Lust, G Coppola… - Computers & fluids, 2010 - Elsevier
A Ciani, W Kreutner, CE Frouzakis, K Lust, G Coppola, K Boulouchos
Computers & fluids, 2010Elsevier
Experiments, simulations, and numerical bifurcation analysis are used to study the
incompressible flow between two opposed tubes with disks mounted at their exits. The
experiments in this axisymmetric geometry show that for low and equal Reynolds numbers,
Re, at both nozzles, the flow remains symmetric about the plane halfway through the nozzle
exits and the stagnation plane is located halfway between the two jets. When Re is
increased past a critical value, asymmetric flow fields are obtained even when the …
Experiments, simulations, and numerical bifurcation analysis are used to study the incompressible flow between two opposed tubes with disks mounted at their exits. The experiments in this axisymmetric geometry show that for low and equal Reynolds numbers, Re, at both nozzles, the flow remains symmetric about the plane halfway through the nozzle exits and the stagnation plane is located halfway between the two jets. When Re is increased past a critical value, asymmetric flow fields are obtained even when the momentum fluxes of the two opposed streams are equal. For unequal Re at the jet exits, when the fixed velocity (and the corresponding Reynolds number, Re1) of one stream is low, the stagnation plane location, SPL, changes smoothly with the Re2. For high enough Re1, a hysteretic jump of SPL is observed. Particle Image Velocimetry and flow visualization demonstrate that within the hysteretic range, the two stable flow fields are anti-symmetric. The experimental setup is also studied with transient incompressible flow simulations using a spectral element solver. It is found that to accurately model the flow, we either need to extend the domain into the nozzles, or impose experimental velocity profiles at the nozzle exits. As in the experiments asymmetric flows are obtained past a critical Re. Finally, bifurcation analysis using a Newton–Picard method shows that the transition from symmetric to asymmetric flows results from the loss of stability of the symmetric flows at a pitchfork bifurcation.
Elsevier
以上显示的是最相近的搜索结果。 查看全部搜索结果