Aerospace and Mechanical Engineering
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AEM faculty spotlight:

Ellen Longmire

Though they hold potential to treat or cure dozens of diseases, embryonic stem cells have considerable ethical baggage. There may exist a middle ground, however, in the form of umbilical blood stem cells. These cells hold great promise for research but lack many of the moral issues accompanying embryonic stem cells. However, due in part to the source, quantity is limited. AEM Professor Ellen Longmire is researching a method that could effectively increase the amount of cells available for research. This is accomplished by preventing the commonplace loss of cells after preservation. Professor Longmire discusses this endeavor, as well as her research into other, traditional problems in fluid dynamics below.

Longmire
Ellen Longmire

What area of research interests you?
In general, all of my projects include experiments. I’m interested in doing experiments where we can discover new physics or perhaps demonstrate concepts that could be used in real products down the line.  In terms of experimentation, I’m interested in finding new ways of measuring things and also of analyzing the resulting measurements to determine things about physics. The purpose of some of our experiments is to provide new types of measurements in fairly simple flows which can be used to help test computational models.
Might you have an example?
One example is that we do experiments on drops coalescing. In general, people can numerically model two drops and their motion.  However, when they coalesce, two drops form one at a tiny location where molecules must rearrange.  The normal computational method simulating macroscopic drops has problems when two bodies form one. People have developed methods to model this that are smooth, efficient, and automated, but are not necessarily based on physics. We are performing experiments in which we document details, like velocity fields internal and external to the drops, that provide test or validation data for computational methods. 
Examples of flows with coalescing drops or bubbles include environmental flows like bubbly flows in the ocean or rivers.  Coalescence is also important in clean up of oil spills on the ocean or in extracting oil from the ground.  In all of these cases, it would be nice to model the flow computationally.  It’s really expensive to do experiments testing specific situations like that, and sometimes you can’t even do the experiment.
Do you have any other projects you are working on?
Another project examines what eddies look like and how they are organized in turbulent flow, specifically close to a wall in a zone called a boundary layer. Boundary layers form around transport vehicles, whether it’s a boat, plane, submarine, or car, or within pipes transporting large amounts of fluid.  In any of these examples, if you can figure out a way to reduce the drag, that would be a huge financial saving as well as a significant fuel saving.
If we can understand the distribution of eddies, maybe we can think about how to change that distribution. Perhaps changing the nature of the surface temporarily or permanently may do that. If you are in a high-performance situation, like with aircraft, maybe you need to only change it for a short time. There may be some actuators with which you could do that.
Tell me a bit about your projects focused on biomedical applications.
We are looking at a way to filter out a chemical added to blood or suspensions of cells in order to preserve them. If you want to preserve blood cells, you have to freeze them or bring them down to a very low temperature. But these cells are packed in a liquid. Just bringing them below freezing temperature will cause these cells to break apart and die. A chemical, like antifreeze, is added to prevent this damage. But when you want to thaw out the suspension for use in a patient, then you need to remove this chemical, otherwise the patient gets sick. The current way to remove this chemical is with a centrifuge, and that works well except that a high percentage of cells in a sample is lost, up to 30 percent. If a sample volume is limited to begin with, that’s a big problem. An example of a limited volume occurs with donated umbilical cord blood. This blood is special because it contains a large number of stem cells. However, its volume is limited. If you lose 30 percent, that’s a big loss and you can’t replace it. Our project is demonstrating a method or device by which we can filter this chemical, DMSO, while preserving a high percentage of the cells.

 


Last Modified: Saturday, 13-Oct-2007 11:15:57 CDT -- this is in International Standard Date and Time Notation