The Fluids Group
This page can direct you to the present status of our research programs. Where possible, we have made links to more detailed information and reviews of the various areas of research.
Many former students and friends have asked about the status of our research on turbulence, mixing, and reactor design and on our future plans. This brief summary is meant for all of you.
I (RSB) am now retired for longer than I can remember. Our recent switch from quarters to semesters at the University and the continued cutting back by me on academic affairs has led to the choice of turning the graduate fluids & CFD course over to others. Thus, my continued efforts are to bug others on the faculty, review all that I have done over the years, and to bring to conclusion a few of the research areas by completing papers or just giving up. Since the research on the flow field within mixing vessels with rotating impellers never really got off the ground due to the complexity of working in a rotating viewing system, nothing additional is planned. To view a photo and drawings of the system you can use this link to the visuals or you can use the drop-down tag above on Mixing Rig. If interested, contact me.
Experiments and computations that involve full-field, time-resolved, velocity vector measurements in the opposed jet system are completed. The opposed-jet data has been used as a tool for a more definitive validation of such a flow. Computationally, it is a fixed system that does not require moving coordinates. The opposed-jet inlets can be laminar, turbulent, or plug and be well defined, thus eliminating cyclic boundary conditions, while the flow within the mixing region is highly turbulent. Some day we might be able to use initial conditions taken from actual three-dimensional experimental results so we could test tracking computationally a turbulent flow in time. In any case, there are no free parameters in the numerical calculations and thus the comparison with experiments should be definitive. A research paper on this multi-year effort is now under review. The following low-resolution, visual link is to one of our older examples of a dynamic visual that shows the average experimental velocity vectors in horizontal planes that scan from the bottom to top of the vessel. Contours of the velocity field are shown either on the top or bottom planes. There is also a 3-D surface representation of the contours in the central region.
A few words are needed on the now abandoned use of a convective view to allow measurement of time-resolved, three-dimensional velocity vectors in a mixing vessel at high Reynolds (a view synchronized with the mixer turbine). The idea is still sound and could allow more fundamental and local parameters (e.g., local turbulent kinetic energy) to be obtained that describe inhomogeneity that is of importance in mixing vessels and can be used to describe trailing impeller vortex structures, baffle-fluid interactions, etc. Such measures can be contrasted with the more usual overall global parameters such as the power per unit volume etc. Local motions must be used to allow prediction of mixing, especially where selectivity is of importance. These measurements must be made under true dynamic conditions where superimposed larger scale motions can influence finer scale mixing processes. The ultimate goal was to model mixing so that computational approaches can make experimental measurements unnecessary. The view must be well based in fundamentals, but at the same time be clearly directed to solving our real world engineering problems.