George   Vradis

George Vradis

Associate Professor

Mechanical Engineering

Journal Articles

Peer Reviewed Journal Publications

  • K.J. Hammad, M.V. Otugen, G.C. Vradis, and E.B. Arik, "Laminar Flow of a Non-Linear Viscoplastic Fluid Through an Axisymmetric Sudden Expansion", Journal of Fluids Engineering, (in review).
  • I.H. Jafri and G.C. Vradis, "The Evolution of Laminar Jets of Herschel-Bulkley Fluids", International Journal of Heat and MassTransfer, Vol. 41, 1998, pp. 3575-3588.
  • K.J. Hammad and G.C. Vradis, "Asymptotic Flow Regimes in Pulsatile Flows of Bingham Plastics", Journal of Fluids Engineering, Vol. 120, No. 1, March 1998, pp. 211-213.
  • G.C. Vradis and K.J. Hammad, "A Strongly-Coupled Bolck-Implicit Solution Technique for Non-Newtonian Convective Heat Transfer Problems", Numerical Heat Transfer- Fundamentals, Part B, Vol. 33, 1998, pp. 79-97.
  • K.J. Hammad, F.Y. Wang, M.V. Otugen, and G.C. Vradis, "Suddenly Expanding Axisymmetric Flow of a Yield-Stress Fluid", 1997 Album of Visualization, No. 14, 1997, pp. 18.
  • G.C. Vradis and M.V. Otugen, "Flow of Non-Newtonian Viscoplastic Fluids Over a Sudden Expansion in a Pipe", Journal of Fluids Engineering, Vol. 119, No. 1, March 1997, pp. 193-200.
  • K.J. Hammad and G.C. Vradis, "Dissipative Cylindrical Couette Flow of Yield-Pseudoplastic Fluids", International Journal of Heat and MassTransfer, Vol. 40, No. 5, 1997, pp. 1243-1248.
  • V.M. Gold, G.C. Vradis, and J.C. Pearson, "Concrete Penetration by High Velocity Projectiles: The Effect of Yield-Strength Modelling", Mathematical Modelling and Scientific Computing, Vol. 6, No. 1, 1996.
  • K.J. Hammad and G.C. Vradis, "Viscous Dissipation and Heat Transfer in Pulsating Flows of a Yield-Stress Fluid", International Communications in Heat and Mass Transfer, Vol. 23, No. 5, 1996, pp. 599-612.
  • G.C. Vradis and K.J. Hammad, "Inertia Effects on the Flow of Bingham Plastics Through Sudden Contractions in a Pipe", Canadian Journal of Chemical Engineering, Vol. 74, No. 4, 1996.
  • K.J. Hammad and G.C. Vradis, "Creeping Flow of a Bingham Plastic Through Axisymmetric Sudden Contractions with Viscous Dissipation", International Journal of Heat and Mass Transfer, Vol. 39, No. 8, 1996, pp. 1555-1568.
  • V.M. Gold, G.C. Vradis, and J.C. Pearson, "Study of Constitutive Models for Concrete Penetration Analysis", ASCE Journal of Engineering Mechanics, Vol. 122, No. 3, 1996, pp. 230-238.
  • V.M. Gold, G.C. Vradis, and J.C. Pearson, "Concrete Penetration of Eroding Projectiles: Experiments and Analysis", ASCE Journal of Engineering Mechanics, Vol. 122, No. 2, 1996, pp. 145-152.
  • G.C. Vradis and K.J. Hammad, "Heat Transfer in Flows of Bingham Fluids Through Axisymmetric Sudden Expansions and Contractions", Numerical Heat Transfer, Part A, Vol. 28, 1995, pp. 339-353.
  • S. Kumar and G.C. Vradis, "Thermal Conductivity of Thin Metallic Films by Electron Transport", Journal of Heat Transfer, Vol. 116, February 1994, pp. 28-34.
  • G.C. Vradis and M.V. Otugen, "Mixing of Multiple Coflowing Confined Laminar Streams", AIAA Journal of Thermophysics and Heat Transfer, Vol. 7, No. 3, July-September 1993, pp. 540-542.
  • G.C. Vradis, M.V. Otugen, S.W. Kim and D.B. Kim, "Round Incompressible Jets with Initially Asymmetric Velocity Distributions", AIAA Journal, Vol. 31, No. 5, May 1993, pp. 814-816.
  • M.V. Otugen, G. Papadopoulos, G.C. Vradis and G. Muckenthaler, "Spanwise Characteristics of the Separated Flow in a Suddenly Expanding Duct", Experiments in Fluids, Vol. 13, No. 2, March 1993, pp. 213-216.
  • G.C. Vradis, J. Dougher and S. Kumar, "Entrance Pipe Flow and Heat Transfer for a Bingham Plastic", International Journal of Heat and Mass Transfer, Vol. 36, February 1993.
  • G.C. Vradis and A.L. Protopapas, "Macroscopic Conductivities for Flows of Bingham Plastics in Porous Media", ASCE Journal of Hydraulics Engineering, Vol. 119, No. 1, January 1993, pp. 95-108.
  • G.C. Vradis, V. Zalak and J. Bentson, "Simultaneous Variable Solutions of the Incompressible Steady Navier-Stokes Equations in General Curvilinear Coordinate Systems", ASME Journal of Fluids Engineering, Vol. 114, September 1992, pp. 299-305.
  • G.C. Vradis and L. Van Nostrand, "Laminar Coupled Flow Downstream of an Asymmetric Sudden Expansion", AIAA Journal of Thermophysics and Heat Transfer, Vol. 6, No 2, April-June 1992, pp. 288-295.
  • J. Bentson and G.C. Vradis, "A Two-Stage Pressure Correction Technique for the Incompressible Navier-Stokes Equations", AIAA Journal, Vol. 28, July 1990, pp. 1155-1156.

Other Publications

Peer Reviewed Conference Papers

  • G.C. Vradis, "Metering Accuracy of Coriolis Mass Flow Meters in Natural Gas Vehicle Filling Stations", to be presented at the the 1998 International Gas Research Conference, San Diego, CA, November 8-11, 1998 (submitted).
  • K.J. Hammad and G.C. Vradis, "Heat Transfer in Laminar Flow of Yield-Pseudoplastic Fluid Over an Axisymmetric Sudden Expansion", to be presented at the Symposium on Fundamentals of Heat Transfer in Separated Flows, 1998 AIAA/ASME Joint Thermophysics and Heat Transfer Conference, Albuquerque, NM, June 15-18, 1998.
  • G.C. Vradis, "Flow of Yield-Stress Fluids in Complex Geometries", Rheology and Fluid Mechanics of Non-Linear Materials, ASME FED-Vol. 243, MD-Vol. 78, Eds: S.G. Advani and D.A. Siginer, 1997, pp.143-150 (Invited Paper at the 1997 ASME IMEC&E, Dallas, TX, November 16-21, 1997).
  • G.C. Vradis and K.J. Hammad, "A Strongly Coupled Block-Implicit Method for Non-Newtonian Flow/Heat Transfer Problems", Heat Transfer Symposium, Energy Week 1997, Houston, Texas, January 28-30, 1997.
  • K.J. Hammad, G.C. Vradis, and M.V. Otugen, "Laminar Flow of a Non-Newtonian Yield-Pseudoplastic Fluid Over an Axisymmetric Sudden Expansion", Proceedings of the 6th International Congress on Fluid Mechanics, Cairo, Egypt, December 29-31, 1996.
  • I.H. Jafri and G.C. Vradis, "The Evolution of Planar and Axisymmetric Yield/Power-Law Jets", Rheology and Fluid Mechanics of Nonlinear Materials, ASME AMD-Vol. 217, pp. 27-36, 1996.
  • K.J. Hammad, M.V. Otugen, G.C. Vradis, and E.B. Arik, "Laminar Axisymmetric Recirculating Flow of a Nonlinear Viscoplastic Fluid", Rheology and Fluid Mechanics of Nonlinear Materials, ASME AMD-Vol. 217, pp. 17-26, 1996.
  • V.M. Gold, G.C. Vradis, and J.C. Pearson, "Concrete Constitutive Modelling in High Velocity Penetration Analysis", Twentieth Army Science Conference; Award Winning Papers, World Scientific, Eds. R. Chait et al., pp. 98-104. Received "Best Paper Award in Engineering Sciences".
  • K.J. Hammad and G.C. Vradis, "Non-Isothermal Controlled Shearing Rate Rheometry of a Yield-Pseudoplastic Fluid: Effects of Shear Heating", Developments and Applications of Non-Newtonian Flows, ASME FED-Vol. 231, MD-Vol. 66, pp. 245-251, 1995.
  • K.J. Hammad and G.C. Vradis, "Viscous Dissipation and Heat Transfer in Pulsatile Flows of A Yield Stress Fluid", Proceedings of the Symposium on Thermal Science and Engineering in Honor of Chancellor Chang-Lin Tien, pp.19-26, San Francisco, California, November 14, 1995.
  • K. Hammad and G.C. Vradis, "Technology Assessment of Gas Turbine Combustors and Their Emissions", Proceedings of the 30th Intersociety Energy Conversion Engineering Conference, Vol. 2, pp.73-82, Orlando, Florida, July 31- August 4, 1995.
  • V.M. Gold, G.C. Vradis, and J.C. Pearson, "Concrete Constitutive Modelling in High Velocity Penetration Analysis", IAMCM 10th International Conference on Mathematical and Computer Modelling, Boston Massachusetts, July 5-8, 1995.
  • G.C. Vradis and K. Hammad, "Heat Transfer in Flows of Non-Newtonian Viscoplastic Fluids Through Sudden Expansions and Contractions in a Pipe", Proceedings of the 4th ASME/JSME Thermal Engineering Joint Conference, Vol. 1, pp. 285-294. Held in Maui, Hawaii, March 19-24, 1995.
  • G.C. Vradis, V. Otugen, and F. Girlea, "Studies Related to Gas Metering Accuracy in Natural Gas Vehicle Filling Stations", Proceedings of the 3rd International Symposium on Fluid Flow Measurement, San Antonio, Texas, March 20-22, 1995.
  • K. Hammad and G.C. Vradis, "Flow of a Non-Newtonian Bingham Plastic Through an Axisymmetric Sudden Contraction: Effects of Reynolds and Yield Numbers", Numerical Methods For Non-Newtonian Fluid Dynamics, ASME FED-Vol. 179, Editors: G.C. Vradis and D.A. Siginer, pp.63-70.
  • V.M. Gold, J.C. Pearson, and G.C. Vradis, "Numerical Simulations of Experiments on Penetration of Concrete Targets", Advances in Numerical Simulation Techniques for Penetration and Perforation of Solids, ASME AMD-Vol. 171, Editors: E.P. Chen and V.K. Luk, pp. 155-166.
  • J.G. Sanchez and G.C. Vradis, "Mixed Convection Heat Transfer Over A Backward Facing Step", Computational Aspects of Heat Transfer Benchmark Problems, ASME HTD-Vol. 258, Editors: B.F. Blackwell and B.F. Armaly, pp. 93-104.
  • G. Papadopoulos, M.V. Otugen, and G.C. Vradis, "Aspect Ratio Effects on the Centerplane Pressure and Flow Structure in a One-Sided Suddenly Expanding Duct", Separated Flows, ASME FED-Vol. 149, Editors: J.C. Dutton and L.P. Purtell, pp. 9-18.
  • G. Papadopoulos, M.V. Otugen, and G.C. Vradis, "Wall Pressure and Near Wall Velocity Studies on the Three-Dimensional Flow Over A Backward Facing Step," Proceedings of the First International Conference on Near-Wall Turbulence, Tempe, AZ, March 15-18, 1993.
  • G.C. Vradis and M.V. Otugen, "The Flow of a Bingham Plastic over a Sudden Expansion in a Pipe", ASME Winter Annual Meeting, Anaheim, CA, November 8-13, 1992, Recent Advances in Non-Newtonian Flows, ASME AMD-Vol. 153, Editor: D.A. Siginer, pp. 129-136.
  • G.C. Vradis and A.L. Protopapas, "Fundamental Relationships for Flows of Bingham Fluids in Porous Media", ASME Winter Annual Meeting, Anaheim, CA, November 8-13, 1992, Recent Advances in Non-Newtonian Flows, ASME FED-Vol. 141, Editor: D.A. Siginer, pp. 57-66.
  • G.C. Vradis, M.V. Otugen, and J.G. Sanchez, "Heat Transfer over a Backward Facing Step: Solutions to a Benchmark Problem", ASME Winter Annual Meeting, Anaheim, CA, November 8-13, 1992, Benchmark Problems for Heat Transfer Codes, ASME HTD-Vol. 222, Editors: B. Blackwell and D. W. Pepper, pp. 27-36.
  • S. Kumar and G.C. Vradis, "Thermal Conductivity of Thin Metallic Films by Electron Transport", National Heat Transfer Conference, San Diego, California, August 9-12, 1992, Heat Transfer on the Microscale, ASME HTD-Vol. 200, Editors: K.S. Udell et al., pp. 55-62.
  • S. Kumar and G.C. Vradis, "Thermal Conduction by Electrons Along Thin Films: Effects of Thickness According to Boltzmann Transport Theory", 1991 ASME Winter Annual Meeting, Atlanta, Georgia, December 1-6, 1991, Micromechanical Sensors, Actuators, and Systems, ASME DSC-Vol. 32, Editors: D. Cho et al., pp. 89-102.
  • G.C. Vradis and S. Kumar, "The Hydrodynamic and Thermal Entrance Flow Problem in a Pipe with Constant Wall Temperature for a Non-Newtonian Bingham Fluid", 1991 ASME National Heat Transfer Conference, Minneapolis, Minnesota, July 28-31, 1991, Convective Heat Transfer and Transport Process, ASME HTD-Vol.168, Editors: A.G. Lavine et al., pp. 9-15.
  • G.C. Vradis, V. Zalak and J. Bentson, "Strongly Implicit Solutions of the Incompressible Steady Navier-Stokes Equations in General Curvilinear Coordinate Systems", First ASME-JSME Fluids Engineering Conference, Portland, Oregon, June 23-26, 1991, General Topics in Fluids Engineering, ASME FED-Vol.107, Editors: F.M. White and K. Kamemoto, pp. 83-90.
  • G.C. Vradis and L. Van Nostrand, "Variable Viscosity Effects on the Laminar Flow and Heat Transfer Downstream Of a Backwards Facing Step", Winter Annual Meeting of the ASME, Dallas, Texas, November 25-30, 1990, Simulation and Numerical Methods in Heat Transfer, ASME HTD-Vol.157, Editor: A.F. Emery, pp. 1-8.

Education

Polytechnic Institute of New York University

Doctor of Philosophy,

Polytechnic Institute of New York University

Master of Science,

National Technical University of Athens, Greece

Bachelor of Science,

Authored + Edited Books

  • Editor, Flows in Manufacturing Processes, 1998, American Society of Mechanical Engineers.
  • Editor, Laminar Flows, 1998, American Society of Mechanical Engineers.
  • Co-Editor, Separated and Complex Flows, 1997, American Society of Mechanical Engineers.
  • Editor, Laminar Flows, 1996, American Society of Mechanical Engineers.
  • Editor, Advances in Computational Heat Transfer, 1995, American Society of Mechanical Engineers.
  • Co-Editor, Separated and Complex Flows, 1995, American Society of Mechanical Engineers.
  • Editor, Numerical Methods for Non-Newtonian Fluid Dynamics, FED-Vol. 179, 1994, American Society of Mechanical Engineers.

Research Interests

Computational fluid dynamics and heat transfer
Non-Newtonian flows
Flow measurement
Combustion
Energy systems