Goodarz Ahmadi is a Clarkson Distinguished Professor, and Robert R. Hill Professor of Mechanical and Aeronautical Engineering at Clarkson University. He is currently serving as the Dean of the Coulter School of Engineering at Clarkson University. He is internationally known for his numerous engineering and scientific research contributions. Professor Ahmadi and has authored two books and over 1000 technical publications (including 400 archival journal articles, more than 500 presentations at national and international conferences and 100 invited talks and short courses). He is serving as a member of editorial board and editorial advisor board of seven international journals. He has been a Fellow of ASME, ISME, and ISCE, and has received several teaching, advising and research awards.

His research interests include particle transport deposition, particle and fiber adhesion and removal, multiphase and granular flows, turbulence modeling and flow through porous media. His research has been supported by the US Environmental Protection Agency, Department of Energy, the National Science Foundation, NASA, Corning, IBM, Xerox, Dura and the New York State Foundation for Science, Technology and Innovation.

Multiphase flows in porous and fractured media occur in many industrial and as well as environmental applications. Experimental and computational modeling methods for studying features of multiphase flows in porous and fractured media are described. The experimental setup of a laboratory-scale flow cell was described in details. It was shown that the gas-liquid flows generate fractal interfaces and the viscous and capillary fingering phenomena are discussed. Experimental data concerning the displacement of two immiscible fluids in the lattice-like flow cell are presented. The flow pattern and the residual saturation of the displaced fluid during the displacement are discussed. Numerical simulation results of the experimental flow in the cell are also presented.
Numerical simulation results for single and multiphase flows through rock fractures are also presented. Fracture geometry studied was obtained from a series of CT scan of an actual rock fracture. Computational results showed that the major losses occur in the regions with smallest apertures. An empirical expression for the fracture friction factor was also described. Applications to CO2 sequestration in underground brine fields and depleted oil reservoir stimulation are discussed. Sample results concerning natural gas production from hydrate reservoir are also presented.

Turbulent flows laden with a dispersed phase of solid particles or liquid droplets are present in many natural phenomena and technological processes such as air pollution and liquid-fuel combustors. In this talk, various existing analytical descriptions for predicting these two-phase flows are reviewed. The main focus is on a collisionless dispersed phase; however, the two-way coupling effects are considered and discussed. The review of various methods is conducted by dividing them into two main categories. The first category includes direct numerical simulation (DNS), large-eddy simulation (LES), and stochastic modeling, which are collectively called the `Lagrangian description’. The second category, under the `Eulerian description’, includes Reynolds averaged Navier-Stokes (RANS) and probability density function (pdf) modeling. The emphasis is placed on application of these approaches for both understanding and prediction of turbulent dispersed phase. The discussion is focused on merits and limitations of these approaches and the nature of predictions offered by them. The underlying mathematical steps involved in RANS and pdf modeling are outlined. The important role of DNS generated data in the development and assessment of other approaches is discussed with the aid of some representative examples in particle-laden homogeneous turbulent flows.

Ali Ashrafizadeh is an assistant professor at the Faculty of Mechanical Engineering, K. N. Toosi University of Technology (KNTU). He is also an adjunct faculty of the Department of Mechanical and Mechatronics Engineering, University of Waterloo (UW) in Canada. Dr. Ashrafizadeh has been graduated from UW in 2000 and has been conducting teaching and research, in collaboration with Professor G. D. Raithby, until 2003 at UW. He has developed the Direct Design Method and is currently the director of the Design of Optimum Systems (DOS) Computational Lab at KNTU.

Engineering thermo-fluid problems are often too difficult to lend themselves to analytical solution methods. Computational Fluid Dynamics (CFD) provides promising numerical methods for handling problems with complex geometry and physics. Numerical Solution of Thermo-Fluid Design Problems (TFDPs) takes more than just CFD. Algorithms are needed to employ CFD, as an analysis tool, to solve a TFDP problem.

Commonly, an iterative procedure is carried out to solve a TFDP. An initial guess is provided by the user (prediction), CFD is employed to solve the corresponding analysis problem (evaluation) and an algorithm is called to change the design variables (correction). Many “standard” algorithms such as optimization methods, control theory approaches and evolutionary procedures are now available and widely used. There are also novel correction methods which apply to certain classes of TFDP. The transpiration technique, used in shape design, is a noticeable example.

It is also possible to formulate the TFDP in a fully coupled manner such that both the flow (state) and design variables appear explicitly in the governing equations. In this formulation, no separate correction algorithm is needed and the solution of the fully-coupled set provides the information relevant to both “analysis” and “design”. Early fully coupled formulations had limitations in applications and were not formulated in a CFD context.

In this talk a fully coupled formulation of a sub-group of TFDPs is introduced which is generally applicable and can be easily implemented in a CFD code. The focus of the talk is on thermo-fluid shape design problems.