Publication Date

8-2015

Date of Final Oral Examination (Defense)

6-15-2015

Type of Culminating Activity

Thesis

Degree Title

Master of Science in Mechanical Engineering

Department

Mechanical and Biomechanical Engineering

Supervisory Committee Chair

Inanc Senocak, Ph.D.

Supervisory Committee Member

Ralph S. Budwig, Ph.D.

Supervisory Committee Member

Trevor Lujan, Ph.D.

Abstract

There has been an increased interest to forecast winds over complex terrain under realistic stability conditions using spatial resolutions that are much finer than the current practice. This goal is realizable thanks to the computational power of graphics processing units (GPUs). This thesis investigates an immersed boundary (IB) formulation and a turbulent inflow boundary condition within a multi-GPU parallel incompressible wind solver. Katabatic flows over a sloped complex terrain surface under stable stratification remain to be one of the least understood subjects in atmospheric turbulence. Prandtl’s analytical solution for laminar katabatic flow is used to develop an IB formulation to impose heat flux boundary conditions, and to assess the formal accuracy of the proposed IB schemes. Direct numerical simulation of turbulent katabatic flow is then performed to investigate the applicability of proposed schemes in the turbulent regime. Additionally, a turbulent inflow boundary condition formulation based on perturbations to the buoyancy field is also developed and studied for a channel flow. Results show that a statistically neutral buoyancy field can serve as a practical method to generate turbulent inflow conditions, and turbulent katabatic flow simulations are sensitive to the specifics of the IB formulation. With these two contributions, the current flow solver is closer to simulating winds over thermally active complex terrain.

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