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Round Jet (round + jet)
Selected AbstractsLarge eddy simulation of flow and scalar transport in a round jetHEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 3 2004Hitoshi Suto Abstract Large eddy simulation (LES) was performed for a spatially developing round jet and its scalar transport at four steps of Reynolds number set between 1200 and 1,000,000. A simulated domain, which extends 30 times the nozzle diameter, includes initial, transitional, and established stage of jet. A modified version of convection outflow condition was proposed in order to diminish the effect of a downstream boundary. Tested were two kinds of subgrid scale (SOS) models: a Smagorinsky model (SM) and a dynamic Smagorinsky model (DSM). In the former model, parameters are kept at empirically deduced constants, while in the latter, they are calculated using different levels of space filtering. Data analysis based on the decay law of jet clearly presented the performance of SGS models. Simulated results by SM and DSM compared favorably with existing measurements of jet and its scalar transport. However, the quantitative accuracy of DSM was better than that of SM at a transitional stage of flow field. Computed parameters by DSM, coefficient for SGS stresses, CR and SGS eddy diffusivity ratio, ,SGS, were not far from empirical constants of SM. Optimization of the model coefficient was suggested in DSM so that coefficient CR was nearly equal in the established stage of jet but it was reduced in low turbulence close to the jet nozzle. © 2004 Wiley Periodicals, Inc. Heat Trans Asian Res, 33(3): 175,188, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20001 [source] Annular liquid jets at high Reynolds numbersINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 2 2003G. Georgiou Abstract The flow of annular liquid jets at high Reynolds numbers is analysed by means of the finite element method and the full-Newton iteration scheme. Results have been obtained for various values of the inner to the outer diameter ratio and for non-zero surface tension, using extremely long meshes. The annular film moves far from the symmetry axis at low values of the Reynolds number. At higher Reynolds numbers, the film moves towards the axis of symmetry and appears close to very far downstream, forming a round jet. Asymptotic results for the radius of the resulting round jet are provided. Copyright © 2003 John Wiley & Sons, Ltd. [source] Computational and experimental fluid dynamics of jet loop reactorAICHE JOURNAL, Issue 10 2009Channamallikarjun S. Mathpati Abstract A computational analysis using standard k-, model, RSM and LES has been carried out for jet loop reactors (JLR) to investigate the mean and turbulence quantities. These simulations have revealed that the flow in JLR was different from the self-similar round jets. RSM and LES showed better agreement with PIV measurements compared with standard k-, model. The modeled turbulence production and transport in k-, model overpredicted those estimated from LES data. To reduce the limitations, modified k-, models have been evaluated for JLR. Also, a hybrid k-, model has been suggested, which was found to perform better than other modified k-, models. This model was also found to hold for stirred tank reactors (STRs). Mixing time analysis has been carried out for JLR and STR at same power consumption. It has been shown that JLR can be inferior to STR if proper nozzle diameter is not selected. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] | ||||||||||