Levich Institute Seminar Announcement, 09/02/2008

Tuesday, 09/02/2008 2:00 PM Steinman Hall, Room #312 (Chemical Engineering Conference Room) Professor Hansong Tang City College of CUNY Civil Engineering Department "Parameter Identification and Instability Modeling of Viscoplastic Fluids Subject to Wall Slip"

ABSTRACT

The speaker will talk about flow of viscoplastic fluids, such as polymers filled with tiny rigid partciles. First, an inverse problem will be discussed for squeeze flow to pull parameters of the fluids and wall slip. Discussion covers a Newtonian fluid with slip, power law without slip, and Herschel-Bulkley fluid with slip. Experimental data, analytical as well as a finite element method (FEM) based numerical solutions of the squeeze flow are used for the analysis and determination of the parameters. It is suggested that the inverse approach can provide solutions for the parameters but the issues of uniqueness and stability need to be properly addressed. Second, instability in capillary flow and a mathematical model will be discussed (instability is considered as unsteadiness of the flow). The model takes compressibility and wall slip of the fluids into account, and it is applied to simulate flows of a polymer, a poly(dimethyl siloxane) or PDMS, and its suspensions with different percentages of glass spheres. The modeling results are in general consistent with experiement data and observation in aspect of shear rate-shear stress relations and range of instability regions.

BRIEF ACADEMIC/EMPLOYMENT BACKGROUND:

Prof. Hansong Tang has been working on fluid mechanics from various backgrounds and numerical methods and simulations. He received the B.S. in Mechanical Eng. from Wuhan Univ. of Hydraulic and Electrical Eng., D.Sc. in Computational Math from Peking Univ., and Ph.D. in Environmental Fluid Mechanics from Georgia Tech. He once worked as a faculty in colleges in China, research scientist at Stevens Institute of Tech, scientist at PNNL/Battelle, and NRC Associate at NRL. In 2007, he joined Dept of Civil Eng. at CCNY as an assistant professor.

CURRENT RESEARCH INTERESTS:

Dr. Tang's current research interests include environmental fluid mechanics, computational physics, and numerical methods.

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