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Assessment and Improvement of Computational Fluid Dynamics Methods for Separated Turbulent Flows at Low Reynolds Numbers.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Assessment and Improvement of Computational Fluid Dynamics Methods for Separated Turbulent Flows at Low Reynolds Numbers./
Author:	Mancuso, Thomas.
Description:	1 online resource (211 pages)
Notes:	Source: Dissertations Abstracts International, Volume: 82-04, Section: B.
Contained By:	Dissertations Abstracts International82-04B.
Subject:	Mechanical engineering. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=27997633click for full text (PQDT)
ISBN:	9798672155777

Assessment and Improvement of Computational Fluid Dynamics Methods for Separated Turbulent Flows at Low Reynolds Numbers.
Mancuso, Thomas.

Assessment and Improvement of Computational Fluid Dynamics Methods for Separated Turbulent Flows at Low Reynolds Numbers. - 1 online resource (211 pages)

Source: Dissertations Abstracts International, Volume: 82-04, Section: B.

Thesis (Ph.D.)--Michigan Technological University, 2020.

Includes bibliographical references

This study investigates the accuracy of Computational Fluid Dynamics (CFD) models to predict heat transfer in turbulent separated flows at low Reynolds numbers. A novel improvement of a Scale Adaptive technique is also presented. A spectrum of turbulence models is used to simulate flow and heat transfer of two geometries; fully developed flow through a staggered tube bank and a square prism in cross flow. Experimental data for both local heat transfer and velocity data are available in the literature for these cases and have been used extensively evaluate various CFD methods. Six unsteady models were used and the results show that the unsteady Shear Stress Transport (SST) model provided good overall accuracy relative to the mean Nusselt number for both cases. However, the SST model failed to accurately predict local variations. The Partially Averaged Navier-Stokes variant of the SST model showed a marked improvement for both cases. The Dynamic Smagorinsky Large Eddy Simulation (LES) showed a much-improved fidelity to the local Nusselt but under predicted the actual values. The computational cost for the LES model was significant. In general, it was found that the computationally expensive models with higher degrees of resolved turbulence did not necessarily return more accurate results.A Scale Adaptive Simulation (SAS) modification of the SST model (SAS-SST) is also used in this study. The SAS approach for the SST model adjusts the production term of the specific dissipation transport equation based on the second velocity derivative. This modification is intended to improve the SST model where local flow accelerations/ decelerations are detected, as occurs in separated flows. However, the local Nusselt number for the two cases considered were found to be generally less accurate than the baseline SST model. In this study a novel modification to this model was made to reduce the SAS contribution near stagnation points in the simulation. This was done through the Kato-Launder and production limiter modification in the SAS production term. The results showed only a slight improvement of the accuracy of the Nusselt number predictions. It is possible that further adjustments to the SAS terms and constants can be made to properly support and complement the stagnation point modification in this study and yield an overall better turbulence model.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2023

Mode of access: World Wide Web

ISBN: 9798672155777Subjects--Topical Terms:

649730
Mechanical engineering.
Subjects--Index Terms:

CFDIndex Terms--Genre/Form:

542853
Electronic books.

Assessment and Improvement of Computational Fluid Dynamics Methods for Separated Turbulent Flows at Low Reynolds Numbers.
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245 1 0 $a Assessment and Improvement of Computational Fluid Dynamics Methods for Separated Turbulent Flows at Low Reynolds Numbers.
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300 $a 1 online resource (211 pages)
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500 $a Source: Dissertations Abstracts International, Volume: 82-04, Section: B.
500 $a Advisor: Mukherjee, Abhijit; Friedrich, Craig R.
502 $a Thesis (Ph.D.)--Michigan Technological University, 2020.
504 $a Includes bibliographical references
520 $a This study investigates the accuracy of Computational Fluid Dynamics (CFD) models to predict heat transfer in turbulent separated flows at low Reynolds numbers. A novel improvement of a Scale Adaptive technique is also presented. A spectrum of turbulence models is used to simulate flow and heat transfer of two geometries; fully developed flow through a staggered tube bank and a square prism in cross flow. Experimental data for both local heat transfer and velocity data are available in the literature for these cases and have been used extensively evaluate various CFD methods. Six unsteady models were used and the results show that the unsteady Shear Stress Transport (SST) model provided good overall accuracy relative to the mean Nusselt number for both cases. However, the SST model failed to accurately predict local variations. The Partially Averaged Navier-Stokes variant of the SST model showed a marked improvement for both cases. The Dynamic Smagorinsky Large Eddy Simulation (LES) showed a much-improved fidelity to the local Nusselt but under predicted the actual values. The computational cost for the LES model was significant. In general, it was found that the computationally expensive models with higher degrees of resolved turbulence did not necessarily return more accurate results.A Scale Adaptive Simulation (SAS) modification of the SST model (SAS-SST) is also used in this study. The SAS approach for the SST model adjusts the production term of the specific dissipation transport equation based on the second velocity derivative. This modification is intended to improve the SST model where local flow accelerations/ decelerations are detected, as occurs in separated flows. However, the local Nusselt number for the two cases considered were found to be generally less accurate than the baseline SST model. In this study a novel modification to this model was made to reduce the SAS contribution near stagnation points in the simulation. This was done through the Kato-Launder and production limiter modification in the SAS production term. The results showed only a slight improvement of the accuracy of the Nusselt number predictions. It is possible that further adjustments to the SAS terms and constants can be made to properly support and complement the stagnation point modification in this study and yield an overall better turbulence model.
533 $a Electronic reproduction. $b Ann Arbor, Mich. : $c ProQuest, $d 2023
538 $a Mode of access: World Wide Web
650 4 $a Mechanical engineering. $3 649730
650 4 $a Fluid mechanics. $3 528155
653 $a CFD
653 $a Heat transfer
653 $a Scale Adaptive Simulation
653 $a Turbulence
653 $a URANS
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710 2 $a ProQuest Information and Learning Co. $3 783688
710 2 $a Michigan Technological University. $b Mechanical Engineering-Engineering Mechanics. $3 1043627
773 0 $t Dissertations Abstracts International $g 82-04B.
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=27997633 $z click for full text (PQDT)