contributor author | F. Durst | |
contributor author | J. C. F. Pereira | |
date accessioned | 2017-05-08T23:27:26Z | |
date available | 2017-05-08T23:27:26Z | |
date copyright | September, 1988 | |
date issued | 1988 | |
identifier issn | 0098-2202 | |
identifier other | JFEGA4-27036#289_1.pdf | |
identifier uri | http://yetl.yabesh.ir/yetl/handle/yetl/104040 | |
description abstract | This paper presents results of numerical studies of the impulsively starting backward-facing step flow with the step being mounted in a plane, two-dimensional duct. Results are presented for Reynolds numbers of Re = 10; 368 and 648 and for the last two Reynolds numbers comparisons are given between experimental and numerical results obtained for the final steady state flow conditions. In the computational scheme, the convective terms in the momentum equations are approximated by a 13-point quadratic upstream weighted finite-difference scheme and a fully implicit first order forward differencing scheme is used to discretize the temporal derivatives. The computations show that for the higher Reynolds numbers, the flow starts to separate on the lower and upper corners of the step yielding two disconnected recirculating flow regions for some time after the flow has been impulsively started. As time progresses, these two separated flow regions connect up and a single recirculating flow region emerges. This separated flow region stays attached to the step, grows in size and approaches, for the time t → ∞, the dimensions measured and predicted for the separation region for steady laminar backward-facing flow. For the Reynolds number Re = 10 the separation starts at the bottom of the backward-facing step and the separation region enlarges with time until the steady state flow pattern is reached. At the channel wall opposite to the step and for Reynolds number Re = 368, a separated flow region is observed and it is shown to occur for some finite time period of the developing, impulsively started backward-facing step flow. Its dimensions change with time and reduce to zero before the steady state flow pattern is reached. For the higher Reynolds number Re = 648, the secondary separated flow region opposite to the wall is also present and it is shown to remain present for t → ∞. Two kinds of the inlet conditions were considered; the inlet mean flow was assumed to be constant in a first study and was assumed to increase with time in a second one. The predicted flow field for t → ∞ turned out to be identical for both cases. They were also identical to the flow field predicted for steady, backward-facing step flow using the same numerical grid as for the time-dependent predictions. | |
publisher | The American Society of Mechanical Engineers (ASME) | |
title | Time-Dependent Laminar Backward-Facing Step Flow in a Two-Dimensional Duct | |
type | Journal Paper | |
journal volume | 110 | |
journal issue | 3 | |
journal title | Journal of Fluids Engineering | |
identifier doi | 10.1115/1.3243547 | |
journal fristpage | 289 | |
journal lastpage | 296 | |
identifier eissn | 1528-901X | |
keywords | Flow (Dynamics) | |
keywords | Foundry coatings | |
keywords | Ducts | |
keywords | Reynolds number | |
keywords | Steady state | |
keywords | Separation (Technology) | |
keywords | Dimensions | |
keywords | Momentum | |
keywords | Channels (Hydraulic engineering) | |
keywords | Equations | |
keywords | Corners (Structural elements) AND Computation | |
tree | Journal of Fluids Engineering:;1988:;volume( 110 ):;issue: 003 | |
contenttype | Fulltext | |