Isabel Fernandez
(Advisor: Prof. Juergen Rauleder)

will defend a master’s thesis entitled,

Evaluation of Boundary Condition Treatments and Environments for Improved Near-Body Solutions in Lattice-Boltzmann Flow Simulations On

Wednesday, May 4 at 9:00 a.m.
Montgomery Knight Building 317

Teams:

https://teams.microsoft.com/l/meetup-join/19%3ameeting_NzUxYTU4MTUtMDRhOC00N2I5LWI2NDMtZDZlZjE0NDI0MGRm%40thread.v2/0?context=%7b%22Tid%22%3a%22482198bb-ae7b-4b25-8b7a-6d7f32faa083%22%2c%22Oid%22%3a%22aa047c8f-5024-4266-af98-3d51c332348d%22%7d
 

Abstract
 This study aims to implement and assess different boundary conditions and methodologies for improving near-body flow solutions for more complex geometric shapes in a Lattice-Boltzmann method (LBM) framework. The Lattice-Boltzmann method is currently being explored as an alternative flow solver for use in high-speed or real-time applications like pilot flight simulators. Because of its localized solution, the highly parallelizable nature of the Lattice-Boltzmann method make it an idea candidate for GPU computing. The Lattice-Boltzmann framework used in this study is a GPU accelerated version of the OpenLB C++ library. The traditional LBM models fluid domain as a set of square lattices aligned to a Cartesian grid. While this allows for a much more computationally efficient analysis, this can result in challenges when modeling solid structures within the fluid flow, as the objects are often represented with a staircase approximation. Different boundary conditions that account for curved geometry are implemented in the current Lattice-Boltzmann framework and different near-body flow parameters are evaluated for complex geometric shapes. The boundary condition treatments were implemented using both no-slip/non-moving wall assumptions and moving-wall/slip assumptions. The effects of resolution and domain size on the near body solution were also analyzed. The effects that the applied boundary conditions had on the far-field flow were analyzed to determine if the near-body flow results had a significant impact on the flow downstream. It was found that different types of boundary treatments had little effect on the near-body flow solution, but the slip vs. no-slip assumption had a significant impact on the near-body results. Namely, by applying a boundary treatment with a slip assumption, the limited flow separation expected around a body was captured, whereas the no-slip boundary treatment typically caused the flow separation field around the object to be overestimated. The no-slip boundary conditions, in addition to giving a less accurate near-body flow solution, also had greater fluctuations and more energy in the far-field, indicating that the no-slip boundary condition may create more wake effects in addition to providing a less accurate near-body solution. 

Committee

• Prof. Juergen Rauleder – School of Aerospace Engineering (advisor)
• Prof. Marilyn Smith – School of Aerospace Engineering
• Prof. Lakshmi Sankar – School of Aerospace Engineering