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University of Pretoria

1. Smith, Lelanie. An interactive boundary layer modelling methodology for aerodynamic flows.

Degree: Mechanical and Aeronautical Engineering, 2012, University of Pretoria

URL: http://hdl.handle.net/2263/25872

Computational fluid dynamics (CFD) simulation is a
computational tool for exploring flow applications in science and
technology. Of central importance in many flow scenarios is the
accurate modelling of the boundary layer phenomenon. This is
particularly true in the aerospace industry, where it is central to
the prediction of drag. Modern CFD codes as applied to modelling
aerodynamic flows have to be fast and efficient in order to model
complex realistic geometries. When considering viscous flows, the
boundary layer typically requires the largest part of computational
resources. To simulate boundary layer flow with most current CFD
codes, requires extremely fine mesh spacing normal to the wall and
is consequently computationally very expensive. Boundary layer
modelling approaches offer considerable computational cost savings.
One boundary layer method which proved to be very accurate is the
two-integral method of Drela (1985). Coupling the boundary layer
solution to inviscid external flow, however, is a challenge due to
the Goldstein singularity, which occurs as separation is
approached. This research proposed to develop a new method to
couple Drela‟s two-integral equations to a generic outer flow
solver in an iterative fashion. The study introduced an auxiliary
equation, which was solved along with the displacement thickness to
overcome the Goldstein singularity without the need to solve the
entire flow domain simultaneously. In this work, the incompressible
Navier-Stokes equations were used for the outer flow. In the
majority of previous studies, the boundary layer thickness was
simulated using a wall transpiration boundary condition at the
interface between viscous and inviscid flows. This boundary
condition was inherently non-physical since it added extra mass
into the system to simulate the effects of the boundary layer.
Here, this drawback was circumvented by the use of a mesh movement
algorithm to shift the surface of the body outward without
regridding the entire mesh. This replaced the transpiration
boundary condition. The results obtained show that accurate
modelling is possible for laminar incompressible flow. The
predicted solutions obtained compare well with similarity solutions
in the case of flat and inclined plates, and with the results of a
NACA0012 airfoil produced by the validated XFOIL code (Drela and
Youngren, 2001). Copyright
*Advisors/Committee Members: Oxtoby, Oliver F. (advisor), Meyer, Josua P. (advisor), Malan, A.G. (advisor).*

Subjects/Keywords: Boundary layer; Two-integral method; Coupling; Auxiliary velocity; Mesh movement algorithm; Displacement thickness; UCTD

Record Details Similar Records

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^{th} Edition):

Smith, L. (2012). An interactive boundary layer modelling methodology for aerodynamic flows. (Masters Thesis). University of Pretoria. Retrieved from http://hdl.handle.net/2263/25872

Chicago Manual of Style (16^{th} Edition):

Smith, Lelanie. “An interactive boundary layer modelling methodology for aerodynamic flows.” 2012. Masters Thesis, University of Pretoria. Accessed October 13, 2019. http://hdl.handle.net/2263/25872.

MLA Handbook (7^{th} Edition):

Smith, Lelanie. “An interactive boundary layer modelling methodology for aerodynamic flows.” 2012. Web. 13 Oct 2019.

Vancouver:

Smith L. An interactive boundary layer modelling methodology for aerodynamic flows. [Internet] [Masters thesis]. University of Pretoria; 2012. [cited 2019 Oct 13]. Available from: http://hdl.handle.net/2263/25872.

Council of Science Editors:

Smith L. An interactive boundary layer modelling methodology for aerodynamic flows. [Masters Thesis]. University of Pretoria; 2012. Available from: http://hdl.handle.net/2263/25872

University of Pretoria

2. Smith, Lelanie. An interactive boundary layer modelling methodology for aerodynamic flows .

Degree: 2012, University of Pretoria

URL: http://upetd.up.ac.za/thesis/available/etd-06262012-100134/

Computational fluid dynamics (CFD) simulation is a
computational tool for exploring flow applications in science and
technology. Of central importance in many flow scenarios is the
accurate modelling of the boundary layer phenomenon. This is
particularly true in the aerospace industry, where it is central to
the prediction of drag. Modern CFD codes as applied to modelling
aerodynamic flows have to be fast and efficient in order to model
complex realistic geometries. When considering viscous flows, the
boundary layer typically requires the largest part of computational
resources. To simulate boundary layer flow with most current CFD
codes, requires extremely fine mesh spacing normal to the wall and
is consequently computationally very expensive. Boundary layer
modelling approaches offer considerable computational cost savings.
One boundary layer method which proved to be very accurate is the
two-integral method of Drela (1985). Coupling the boundary layer
solution to inviscid external flow, however, is a challenge due to
the Goldstein singularity, which occurs as separation is
approached. This research proposed to develop a new method to
couple Drela‟s two-integral equations to a generic outer flow
solver in an iterative fashion. The study introduced an auxiliary
equation, which was solved along with the displacement thickness to
overcome the Goldstein singularity without the need to solve the
entire flow domain simultaneously. In this work, the incompressible
Navier-Stokes equations were used for the outer flow. In the
majority of previous studies, the boundary layer thickness was
simulated using a wall transpiration boundary condition at the
interface between viscous and inviscid flows. This boundary
condition was inherently non-physical since it added extra mass
into the system to simulate the effects of the boundary layer.
Here, this drawback was circumvented by the use of a mesh movement
algorithm to shift the surface of the body outward without
regridding the entire mesh. This replaced the transpiration
boundary condition. The results obtained show that accurate
modelling is possible for laminar incompressible flow. The
predicted solutions obtained compare well with similarity solutions
in the case of flat and inclined plates, and with the results of a
NACA0012 airfoil produced by the validated XFOIL code (Drela and
Youngren, 2001). Copyright
*Advisors/Committee Members: Oxtoby, Oliver F (advisor), Meyer, Josua P (advisor), Malan, A.G (advisor).*

Subjects/Keywords: Boundary layer; Two-integral method; Coupling; Auxiliary velocity; Mesh movement algorithm; Displacement thickness; UCTD

Record Details Similar Records

❌

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^{th} Edition):

Smith, L. (2012). An interactive boundary layer modelling methodology for aerodynamic flows . (Masters Thesis). University of Pretoria. Retrieved from http://upetd.up.ac.za/thesis/available/etd-06262012-100134/

Chicago Manual of Style (16^{th} Edition):

Smith, Lelanie. “An interactive boundary layer modelling methodology for aerodynamic flows .” 2012. Masters Thesis, University of Pretoria. Accessed October 13, 2019. http://upetd.up.ac.za/thesis/available/etd-06262012-100134/.

MLA Handbook (7^{th} Edition):

Smith, Lelanie. “An interactive boundary layer modelling methodology for aerodynamic flows .” 2012. Web. 13 Oct 2019.

Vancouver:

Smith L. An interactive boundary layer modelling methodology for aerodynamic flows . [Internet] [Masters thesis]. University of Pretoria; 2012. [cited 2019 Oct 13]. Available from: http://upetd.up.ac.za/thesis/available/etd-06262012-100134/.

Council of Science Editors:

Smith L. An interactive boundary layer modelling methodology for aerodynamic flows . [Masters Thesis]. University of Pretoria; 2012. Available from: http://upetd.up.ac.za/thesis/available/etd-06262012-100134/