Thesis
Numerical investigation of the shear stress distribution resulting from a turbulent impinging jet
Washington State University
Master of Science (MS), Washington State University
08/2015
Handle:
https://hdl.handle.net/2376/103261
Abstract
Erosion is a natural process that has increased it rates of occurrence due to natural and anthropogenic activities. Therefore, it has become a major concern that has high impact on human health, water quality and quantity, and ecosystems conservation. Erosion of cohesive soils is a complex process that depends not only on physical, chemical, and biological properties, but also on the interaction between them. The linear excess shear stress equation is a widely-used model to quantify soil erodibility, where the erosion rate for a given flow is determined by two parameters: (1) the critical shear stress and (2) the detachment, or erodibility, coefficient. Laboratory and field experiments have been conducted to estimate soil erodibility. Because erodibility has been shown to be a site specific soil property in-situ tests are preferable. The jet erosion test has emerged as a cost-effective tool to measure cohesive soil erodibility. It is based on the maximum shear stress produced by a submerged jet impinging normal to the soil surface. There exist several limitations in the data analysis procedure including an empirical model used to calculate the shear stress applied by the jet. Previous studies have developed relations for the maximum shear stress, but little agreement has been achieved between authors. In the present study computational fluid dynamics (CFD) is applied to develop a numerical model to investigate the distribution of shear stress. The numerical results were compared with the model currently used for jet test results as well as alternative models. Considerable differences were observed between the different models. An additional mathematical model was developed from the simulated maximum shear stress. The obtained model reports values as large as 2.5 times the current test values. The differences in erosion rates are on the order of 136%. Considering that this CFD-derived model calculatesthe maximum shear stress using the near-wall velocity gradient, it can become an improvement to the test data analysis. Additionally, the Grid Convergence Index method was applied to estimate the uncertainty in the predicted maximum shear stress due to discretization in the numerical results. The uncertainty has been quantified from 19% to 72% of the fine solution.
Metrics
10 File views/ downloads
42 Record Views
Details
- Title
- Numerical investigation of the shear stress distribution resulting from a turbulent impinging jet
- Creators
- Veronica Margarita Carrillo Serrano
- Contributors
- John Petrie (Chair)Jennifer C Adam (Committee Member) - Washington State University, Civil and Environmental Engineering, Department ofBrian K Lamb (Committee Member) - Washington State University, Civil and Environmental Engineering, Department of
- Awarding Institution
- Washington State University
- Academic Unit
- Civil and Environmental Engineering, Department of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; [Pullman, Washington] :
- Number of pages
- 142
- Identifiers
- 99900525049301842
- Language
- English
- Resource Type
- Thesis