Program and Mission Statement:

High shear mixers are broadly employed in the Chemical Process Industries to produce emulsions, dispersions, multiphase gel networks, etc., and to control particle size. Despite their widespread use, there is almost no fundamental basis by which to theoretically predict or experimentally assess their performance. As a result, process development, scaleup and operation are often by trial and error, leading to higher processing costs, start-up problems and lost time to market. It is proposed to develop a fundamental understanding, at least on a mechanistic basis, of the controlling fluid dynamics for single and multiphase processes, in order to bring the state of the art for high shear devices towards that available for processing in stirred vessels and static mixers. This will be accomplished via a comprehensive program that includes mechanistic modeling, computer simulation and definitive experiments.

Experiment and theory will focus on prototype or targeted rotor-stator mixers that capture the essential features of this class of equipment. A novel Laser Doppler Anemometry (LDA) technique will be used to measure the velocity field relative to the stationary stator and relative to the spinning rotor. The data will be employed to develop and validate a state of the art sliding mesh CFD code to assess device performance and predict power draw (also measured). Mechanistic models and correlating theories will be developed which apply to dilute dispersions of oils in water, production of stable emulsions and crystal/slurry grinding. Drop size distribution data will be acquired using a unique video microscope to validate the models and provide a basis for data correlation. While theory and experiment will focus on Newtonian fluids, we will lay a foundation to extend the results to more complex rheological behavior.

Since there is no fundamental body of literature to serve as a starting point, the proposed work is exploratory in nature, making it difficult to confidently predict its outcome. However, it is expected that the knowledge gained from consideration of the prototype / targeted mixers will lead to performance criteria for the entire class of rotor-stator devices, as well as a fundamental basis for building and extrapolating equipment specific correlations. The work will provide a basis for process design and scaleup, and may lead to changes in mixer design. Beyond what is discussed herein, future work will address more complex Rheology, refinement of the knowledge base and more detailed assessment of vendor specific devices.
 

Guidelines for Industrial Advisory Board Membership:

The University of Maryland, High Shear Mixing Research Program will be overseen by an Industrial Advisory Board. The board will guide the program’s research direction and for providing the resources to carry out the work. The Industrial Advisory Board will represent a consortium comprised of equipment users / chemical manufactures, vendors of high shear mixer hardware and CFD software, and other relevant organizations. The program’s Research Director (RVC) will also be a member of the board. All organizations that have been invited to join prior to October 1, 1998 may choose to participate. Participation by others shall be by invitation of the board. While several employees may be involved with the program, each member organization shall designate a primary contact to serve as the official board member. The primary contact may change as reasonably needed.

The mission of the research program is to develop a fundamental understanding, at least on a mechanistic basis, of the controlling fluid dynamics for single and multiphase processes, in order to bring the state of the art for high shear devices towards that available for processing in stirred vessels and static mixers. To this end, most of the work will be generic in nature. As required by University of Maryland policy, the research results will be presented at public forums and be published in the open literature. However, consortium members will have early access to the results. These will be in the form of MS / PhD theses, progress reports and presentations, available in hard copy and / or at a password protected website. Consortium members may want to share their own information or intellectual property to advance the research. Others may want to interpret research results within a context related to their businesses. When such material is considered to be confidential, an appropriate confidential information disclosure agreement will be executed.

The Advisory Board will meet twice per year (May and October) to discuss research results, assess progress and guide future directions. All employees of the member organizations are invited to attend and participate in the discussions. However, the suggestions of each member organization, as set forth by the primary contact (or designee), shall be given equal weight.

Each member organization will contribute an equitable share of resources to the research program, as outlined below:
 

a)	The basic membership fee is $ 12,500 per year.
b)	A member organization can reduce its cash contribution by providing equipment or contributions in kind. Examples include the fair market value of high shear mixers, machine shop services, software license fees and high-speed computer time. In some cases, the member organization can contribute manpower to work on a specific project.
c)	Companies who are funding related projects with the Research Director (RVC), under a contract to the University of Maryland, can reduce their cash contribution to the extent that they share results that are relevant to the high shear program.
d)	In special circumstances, other provisions can be made with the consent of the advisory board.