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A Velocity Decomposition Approach fo...

Chen, Yang.

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A Velocity Decomposition Approach for Three-Dimensional Unsteady Viscous Flow at High Reynolds Number.

Record Type:	Electronic resources : Monograph/item
Title/Author:	A Velocity Decomposition Approach for Three-Dimensional Unsteady Viscous Flow at High Reynolds Number./
Author:	Chen, Yang.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 2017,
Description:	155 p.
Notes:	Source: Dissertation Abstracts International, Volume: 78-11(E), Section: B.
Contained By:	Dissertation Abstracts International78-11B(E).
Subject:	Naval engineering. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=10612084
ISBN:	9781369902181

A Velocity Decomposition Approach for Three-Dimensional Unsteady Viscous Flow at High Reynolds Number.
Chen, Yang.

A Velocity Decomposition Approach for Three-Dimensional Unsteady Viscous Flow at High Reynolds Number. - Ann Arbor : ProQuest Dissertations & Theses, 2017 - 155 p.

Source: Dissertation Abstracts International, Volume: 78-11(E), Section: B.

Thesis (Ph.D.)--University of Michigan, 2017.

A velocity decomposition method is developed for the solution of three-dimensional, unsteady flows. The velocity vector is decomposed into an irrotational component (viscous-potential velocity) and a vortical component (vortical velocity). The vortical velocity is selected so that it is zero outside of the rotational region of the flow field and the flow in the irrotational region can thus be solely described by the viscous- potential velocity. The formulation is devised to employ both the velocity potential and the Navier-Stokes-based numerical methods such that the field discretization required by the Navier-Stokes solver can be reduced to only encompass the rotational region of the flow field and the number of unknowns that are to be solved by the Navier-Stokes solver is greatly reduced. A higher-order boundary-element method is used to solve for the viscous potential by applying a viscous boundary condition to the body surface. The finite-volume method is used to solve for the total velocity on a reduced domain, using the viscous-potential velocity as the boundary condition on the extent of the domain. The viscous-potential velocity and the total velocity are time dependent due to the unsteadiness in the boundary layer and the wake. A two-way coupling algorithm is developed to tightly couple the two solution procedures in time. The velocity-decomposition-coupled solver developed in this work is used to solve three-dimensional, laminar and turbulent unsteady flows. For turbulent flows, the solver is applied for both Unsteady-Reynolds-Averaging-Navier-Stokes and Large-Eddy-Simulation computations. The solver is demonstrated to be capable of solving problems with realistic geometries. Preliminary results for 3D lifting flow are also presented. By using the velocity-decomposition-coupled solver, the solution can be determined on a greatly reduced domain and have the same accuracy as that calculated by a conventional Navier-Stokes solver on a large domain. For some test cases, the number of unknowns in the computational mesh is reduced up to 50%.

ISBN: 9781369902181Subjects--Topical Terms:

3173824
Naval engineering.

A Velocity Decomposition Approach for Three-Dimensional Unsteady Viscous Flow at High Reynolds Number.
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245 1 2 $a A Velocity Decomposition Approach for Three-Dimensional Unsteady Viscous Flow at High Reynolds Number.
260 1 $a Ann Arbor : $b ProQuest Dissertations & Theses, $c 2017
300 $a 155 p.
500 $a Source: Dissertation Abstracts International, Volume: 78-11(E), Section: B.
500 $a Adviser: Kevin John Maki.
502 $a Thesis (Ph.D.)--University of Michigan, 2017.
520 $a A velocity decomposition method is developed for the solution of three-dimensional, unsteady flows. The velocity vector is decomposed into an irrotational component (viscous-potential velocity) and a vortical component (vortical velocity). The vortical velocity is selected so that it is zero outside of the rotational region of the flow field and the flow in the irrotational region can thus be solely described by the viscous- potential velocity. The formulation is devised to employ both the velocity potential and the Navier-Stokes-based numerical methods such that the field discretization required by the Navier-Stokes solver can be reduced to only encompass the rotational region of the flow field and the number of unknowns that are to be solved by the Navier-Stokes solver is greatly reduced. A higher-order boundary-element method is used to solve for the viscous potential by applying a viscous boundary condition to the body surface. The finite-volume method is used to solve for the total velocity on a reduced domain, using the viscous-potential velocity as the boundary condition on the extent of the domain. The viscous-potential velocity and the total velocity are time dependent due to the unsteadiness in the boundary layer and the wake. A two-way coupling algorithm is developed to tightly couple the two solution procedures in time. The velocity-decomposition-coupled solver developed in this work is used to solve three-dimensional, laminar and turbulent unsteady flows. For turbulent flows, the solver is applied for both Unsteady-Reynolds-Averaging-Navier-Stokes and Large-Eddy-Simulation computations. The solver is demonstrated to be capable of solving problems with realistic geometries. Preliminary results for 3D lifting flow are also presented. By using the velocity-decomposition-coupled solver, the solution can be determined on a greatly reduced domain and have the same accuracy as that calculated by a conventional Navier-Stokes solver on a large domain. For some test cases, the number of unknowns in the computational mesh is reduced up to 50%.
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