Insight Derived From High Order Structured Finite Difference CFD Simulations of Flow Past Generic Simplified Car Models

Search for this publication on Google Scholar
Henry, M. (2016). Insight Derived From High Order Structured Finite Difference CFD Simulations of Flow Past Generic Simplified Car Models. Unc Charlotte Electronic Theses And Dissertations.
Download PDF

Analytics

58 views ◎
24 downloads ⇓


Abstract

This thesis focuses upon using a high-order finite-difference method on a structured overset grid to study flow features around a generic simplified car model adjusting mesh refinements, rear slant angles, solvers, and turbulence models. These processes are explored to develop a procedure for simulating more complex and realistic car models. Three different mesh refinements from 17 to 108 million vertices were tested with three different solvers (RANS, URANS, and DES) on an Ahmed body with a subcritical slant angle ascertain the optimum mesh parameters for subsequent simulations. Using a 57 x 10^6 vertex mesh, multiple rear slant angles near the critical angle (30 degrees) were investigated with RANS and URANS approaches to compare drag, lift, and flow fields with experimental and CFD data found in literature. Similar trends were observed in CFD predictions and experimental data, including flow separation at the critical angle (30 degrees), but all predicted results were within 15% of experimental measurements for both time-averaged and unsteady simulations. At the sub-critical angle (25 degrees), CFD predictions using multiple hybrid RANS/LES approaches were compared against time-averaged and unsteady experimental measurements. These did not disagree with previous results and drag values were over predicted by a maximum of 4%, while lift values were under predicted by a maximum of 15% when compared to experimental results. Subsequent studies investigating elongated mesh refinement areas were inconclusive. The procedures outlined compare reasonably well to experimental data and can be used as a starting point for simulating more realistic models including complex dynamic pitch, heave, and roll simulations involving road vehicles.

Details
Author

Henry, Maxwell

Title

Insight Derived From High Order Structured Finite Difference CFD Simulations of Flow Past Generic Simplified Car Models

Physical Description

1 online resource (91 pages) : PDF

Date

2016

Degree Granting Institution

University of North Carolina at Charlotte

Abstract

This thesis focuses upon using a high-order finite-difference method on a structured overset grid to study flow features around a generic simplified car model adjusting mesh refinements, rear slant angles, solvers, and turbulence models. These processes are explored to develop a procedure for simulating more complex and realistic car models. Three different mesh refinements from 17 to 108 million vertices were tested with three different solvers (RANS, URANS, and DES) on an Ahmed body with a subcritical slant angle ascertain the optimum mesh parameters for subsequent simulations. Using a 57 x 10^6 vertex mesh, multiple rear slant angles near the critical angle (30 degrees) were investigated with RANS and URANS approaches to compare drag, lift, and flow fields with experimental and CFD data found in literature. Similar trends were observed in CFD predictions and experimental data, including flow separation at the critical angle (30 degrees), but all predicted results were within 15% of experimental measurements for both time-averaged and unsteady simulations. At the sub-critical angle (25 degrees), CFD predictions using multiple hybrid RANS/LES approaches were compared against time-averaged and unsteady experimental measurements. These did not disagree with previous results and drag values were over predicted by a maximum of 4%, while lift values were under predicted by a maximum of 15% when compared to experimental results. Subsequent studies investigating elongated mesh refinement areas were inconclusive. The procedures outlined compare reasonably well to experimental data and can be used as a starting point for simulating more realistic models including complex dynamic pitch, heave, and roll simulations involving road vehicles.

Genre

masters theses

Subjects--Topics

Mechanical engineering
Engineering
Automobiles--Design and construction

Degree

M.S.

Keywords

Ahmed Body
CFD
Finite-Difference
Overflow
Overset Grids
Road Vehicle Dynamics

Subject Area

Mechanical Engineering

Advisor(s)

Uddin, Mesbah

Committee Members

Tkacik, Peter
Ramaprabhu, Praveen

Degree Note

Thesis (M.S.)--University of North Carolina at Charlotte, 2016.

Rights Statement

This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s). For additional information, see http://rightsstatements.org/page/InC/1.0/.

Rights Holder Information

Copyright is held by the author unless otherwise indicated.

Identifier

Henry_uncc_0694N_11141

Permalink

http://hdl.handle.net/20.500.13093/etd:1390