When Engineers and Biologists Meet

There is both tremendous potential for mechanical engineers to contribute to biology and a wide range of biological problems that push the state-of-the art in engineering. My research uses experimental methods, particularly Particle Image Velocimetry (PIV), and Computational Fluid Dynamics to study a wide range of applied and biological flows.  Fluid mechanical systems that I have worked on include human engineered mechanical devices and naturally occurring systems. In this seminar, I’ll talk about two of these, artificial heart pumps and suction feeding fish.  In addition to spanning the range between man-made and natural systems, these two also straddle the continuum between traditional engineering design and basic science.

A ventricular assist device (VAD) is a mechanical pump that aids, but does not replace, the native heart. All of the currently available pumps have a limited life because of either the damage that they cause to blood or mechanical design life.  A pump with magnetic bearings offers the potential of eliminating damage and increasing design life of the pump. Flow within the pump is three-dimensional, turbulent, and time varying (unlike most industrial pumps), yet critical because it determines overall pump performance and potentially contributes to both red blood cell damage and blood clotting. I measured (PIV) and modeled (CFD) the flow within several regions the pump and in order to identify regions of potential blood damage due to high shear stress and or stagnation.  This study was the first of its kind to characterize the flow within all regions of a rotary blood pump and was similarly the first study of the effects of time-varying flow through this type of device.

The suction feeding fish generates a flow field external to its head that draws the prey towards the mouth. This is a very fast event, typically lasting less than 40 msec. Prior to this work, there were very few empirical measurements or detailed modeling of the fluid mechanics of suction feeding, particularly the temporal and spatial patterns of velocity and pressure of water in front of the fish. To characterize the flow in front of suction feeding fish, I trained bluegill sunfish and largemouth bass to feed within a laser sheet, from which I made measurements with high spatial (<1mm) and temporal (500 Hz) resolution with PIV. Additionally, some fish were surgically implanted with a pressure transducer to measure the time resolved pressures inside the mouth cavity and the relationship of this to generated fluid speed. A Computational Fluid Dynamics (CFD) model is being developed to complement the measurements.