Direct numerical simulation of jets in cross-flow

Yao, Y. and Petty, D. and Barrington, P. and Yao, J. and Mason, P. (2007) Direct numerical simulation of jets in cross-flow. International Journal of Computational Fluid Dynamics, 20 (5). pp. 279-286. ISSN 1061-8562

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Official URL: http://dx.doi.org/10.1080/10618560600909945

Abstract

Direct numerical simulation (DNS) of jets in cross-flow (JICF) has been carried out in this study, aiming for the investigation of vortex structure formation and evolution process associated with JICF. A recently developed DNS code is used, which solves three-dimensional (3D) compressible unsteady Navier–Stokes (NS) equations using high-order finite differences and multi-block structure grid treatment for complex geometry. Jet flow from a square duct, perpendicular to the mainstream flow, is introduced and the flow Reynolds number is 100 based on the jet duct diameter (D) and free-stream quantities. Two-dimensional (2D) calculations using various jet to free-stream velocity ratio (R = V jet/V free) reveals different vortex patterns and a further 3D study continues focusing on a velocity ratio of R = 2, for which complex vortex structure is produced. It is found from the 3D simulation that a counter-rotating vortex pair (CRVP) forms immediately after the jet exits, as observed from the experimental test and reproduced by other numerical simulations. The CRVP originates from the near wall viscous layer and its core position moves away from the wall as it evolves downstream. For the condition simulated, the CRVP is finally weakened (due to viscous diffusion) at about 1.6D downstream from the centre of the jet exit. No asymmetric CRVP has been observed, which was reported by other researchers for high-Reynolds number simulations.

Item Type:Article
Additional Information:Direct numerical simulation (DNS) of jets in cross-flow (JICF) has been carried out in this study, aiming for the investigation of vortex structure formation and evolution process associated with JICF. A recently developed DNS code is used, which solves three-dimensional (3D) compressible unsteady Navier–Stokes (NS) equations using high-order finite differences and multi-block structure grid treatment for complex geometry. Jet flow from a square duct, perpendicular to the mainstream flow, is introduced and the flow Reynolds number is 100 based on the jet duct diameter (D) and free-stream quantities. Two-dimensional (2D) calculations using various jet to free-stream velocity ratio (R = V jet/V free) reveals different vortex patterns and a further 3D study continues focusing on a velocity ratio of R = 2, for which complex vortex structure is produced. It is found from the 3D simulation that a counter-rotating vortex pair (CRVP) forms immediately after the jet exits, as observed from the experimental test and reproduced by other numerical simulations. The CRVP originates from the near wall viscous layer and its core position moves away from the wall as it evolves downstream. For the condition simulated, the CRVP is finally weakened (due to viscous diffusion) at about 1.6D downstream from the centre of the jet exit. No asymmetric CRVP has been observed, which was reported by other researchers for high-Reynolds number simulations.
Keywords:Direct numerical simulation, Cross-flow, Jets, Vortex structure
Subjects:H Engineering > H141 Fluid Mechanics
H Engineering > H400 Aerospace Engineering
Divisions:College of Science > School of Engineering
ID Code:5430
Deposited By: Jun Yao
Deposited On:07 May 2012 19:07
Last Modified:07 May 2012 19:07

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