Density Currents Over Smooth and Rough Surfaces Nic Johnson/Environmental Science/Senior/Local Utilities, Sustainable Development using GIS Dr. Kiran Bhaganagar, Raghib Chowdhury Department of Mechanical Engineering BACKGROUND: What behavior is exhibited by a fluid mixture? This depends on the properties of the components of the mixture and the environment. The densities of each substance will effect the mixture. How will this density current over the specific terrain or in the atmosphere of the environment effect how the mixture behaves? MAIN TOPIC: How does density effect the flow of a substance in a system, over various rough versus smooth surfaces? APPLICATIONS: A better understanding of how rough surfaces effect density currents will help in mitigating disasters such as marine chemical spills, transportation of pollution in freshwater systems, and air pollution due to volcanic eruption or urban/rural fires.

METHODOLOGIES Simulations with the open-source Computational Fluid Dynamics software package OpenFOAM are run and opened with Paraview, another open-source program used for visualization and analysis. Output from OpenFOAM can be tweaked by the user for a desired ‘resolution’ of the simulation. Greater accuracy is computationally complex and simulations can require quite a bit of processing power. The lab is equipped with Himalaya, a supercomputer which can be used as a resource for detailed simulations. Paraview is used to visualize the output from the OpenFOAM simulations and has the capacity for 1-D plots, and 2-D & 3-D plots and renderings. Visualizations will have user defined boundary conditions (parameters), which can include the domain in x, y, z coordinates, the location of the gate, roughness etc., which can be used to better understand the behaviour of the current over the specific roughness, be it sparse or dense. Navier-Stokes Equation : This is the governing equation used in the study of the motion of non-turbulent, fluid substances. Can be used to model turbulent flow when used in the Reynolds-averaged Navier-Stokes form. Millennium prize from Clay Mathematics Institute.