Multiscale, Multi-Physics Modeling Projects

 

Physics- and data-driven high throughput development of high entropy alloys 

High entropy alloys (HEAs) have shown potential to improve on the performance of legacy materials, thus characterizing the relationships between the composition, material properties, and microstructure of HEAs is of great interest. However, predicting these characteristics presents significant challenges due to the complex, multi-component nature of HEAs and the resulting large design space. To address this challenge, a multi-physics simulation framework and data-driven surrogate modeling approach are implemented, to provide a method to rapidly assess how changes in HEA composition will lead to changes in material properties and microstructure.

Physics- and data-driven framework for high entropy alloys

Environmental Transport

The prediction of transport of contaminants, sediment, or other solutes in rivers and streams is an important problem in environmental engineering. When fluid streams over a rough, permeable bed, as is common in these flows, the flow in the interface region (the so-called hyporheic zone) is complex and multi-scale, leading to exchange of solute between the bed and the free stream, and long-range dispersion that is not well-described by familiar advection-diffusion equations. In order to understand this process and develop predictive models, we perform large eddy simulation (LES) of the dispersion of fluid and particles in this interface region, and use mesoscale modeling techniques to quantify the anomalous long-range diffusion of solutes downstream.
3D geometry for LES of flow over a rough, permeable bed
Streamwise velocity snapshot for flow over a permeable bed

Converging streamlines upstream of a regurgitant mitral valve orifice

Mitral valve regurgitation modeled as turbulent jets through a single or double orifice

Mitral Valve Flow

The mitral valve in the heart separates the left atrium from the left ventricle. Under normal conditions, this is a one-way valve that opens to allow flow from the atrium to the ventricle, and closes to block flow as heart pumps blood from the ventricle through the aorta. However, over 5 million Americans are affected, to some degree of severity, by mitral regurgitation (MR), in which the valve leaks and allows blood flow back into the atrium during pumping. In severe cases, MR requires repair to avoid eventual heart failure. MR can often be observed in an echocardiogram, but its severity can be difficult to quantify. In our group, we are collaborating with researchers in Northwestern’s Feinberg School of Medicine to determine whether computational simulation can be used to aid in diagnosing the severity of MR based on available imaging. Starting with simple geometrical models, we are studying the effects of valve orifice shape and topology, with a goal of adding detail to the models including fluid-structure interaction and complex, patient-specific geometries.

Contact

Greg Wagner
Associate Professor
Department of Mechanical Engineering
Northwestern University
gregory.wagner@northwestern.edu
847-491-4138