Jie Chen

Blood Flow Through Stenosed Carotid and Coronary Arteries with Complete Bypass

The blood flow through stenosed carotid and coronary arteries with a complete bypass graft are investigated by using computational fluid dynamics tools. A non-Newtonian Carreau model is applied to mimic the rheology of the blood in non-diabetic and diabetic patients. Different anastomotic angles, bypass graft length, and locations of the stenosis are analyzed as function of the extent of plaque occlusion in the artery. The effects of type-II diabetes mellitus is also investigated. The results show that the flow features, including pressure drop cross the stenosis and the shear stress on artery walls, are all influenced by these parameters; a systematic analysis is conducted to derive information on graft design so as to minimize the possibility of the restenosis in the host artery with bypass graft implantation.

Dispersion of Carbon Nanotubes in Resin Systems using Chaotic Mixing

Carbon nanotubes reinforced polymer nanocomposites have been the subject of much investigation in recent literature. Uniform distribution and dispersion of carbon nanotubes in polymer matrices is critical for realizing the full potential of composites incorporating the nanotubes; however, dispersion of carbon nanotubes remains a challenging problem. This study explores the use of chaotic fluid mixing phenomenon for dispersing carbon nanotubes in resin systems. Chaotic advection exponentially stretches and folds fluid in situ and the trajectories of the periodic points in the flow form a braid that leads to topological chaos. It is expected that topological chaos could significantly enhance the chaotic mixing of carbon nanotubes. Computational simulations are used to analyze dispersion effectiveness and the flow features as a function of the dispersion process parameters.

Computational Modeling of Polymer Flow in Mircocavities through a Microscreen

This study investigates a new technique for rapid replication of electroforming micromolds with integral microscreens. The process is based on injection molding or hot embossing of plastic replicates with integral metallic screens onto a LIGA-fabricated master microtool, to produce sacrificial electroforming molds in which the metallic screen acts as the conducting base and the plastic features provide insulating sidewalls for electrodeposition of the desired metallic micropart. A computational model is de- veloped for the polymer flow during the fabrication of electro- forming micromolds incorporating the temperature dependent, non-Newtonian rheology of the polymer melts. The model is used to analyze the effects of the process parameters and micro-feature geometry on the polymer flow patterns.

Publications

1. C-10-02: J. Chen and R. Pitchumani, "Dispersion of Carbon Nanotubes in Resin Systems using Chaotic Mixing," Paper No. 35, Proceedings of the 10th International Conference on Flow Processes in Composite Materials, Ascona, Switzland, July 11-15, 2010, 5 pp., 2010.
2. C-10-06: J. Chen and R. Pitchumani, "Computational Modeling of Polymer Flow in Microcavities through a Microscreen," Paper No. IMECE2010-38675, Proceedings of the ASME International Mechanical Engineering Congress and Exposition, Vancouver, British Columbia, Canada, November 12-18, 2010, 9 pp., 2010.