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Engineering Mathematics
Review of Viscous Flows
Review of Computational Fluid Mechanics
Review of Turbulence and Turbulence Modeling

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ME 637 The National Science Foundation
 Aerosols
Introduction to Aerosols | Drag, Lift Forces | Aerosol Kinetics | Virtual Mass, Basset Forces & BBO Equation | Nonspherical Particles | Brownian Motions | Particle Deposition Mechanisms | Electrodynamics | Aerosol Coagulation |

Drag Force

Compressibility Effect

For high-speed flows with high Mach number, the compressibility could affect the drag coefficient. Many expressions were suggested in the literature to account for the effect of gas Mach number on the drag force. Henderson (1976) suggested two expressions for drag force acting on spherical particles for subsonic and supersonic flows. Accordingly, for subsonic flow

(11)

where M is the Mach number based on relative velocity, , and is the molecular speed ratio, where γ is the specific heat ratio. For the supersonic flows with Mach numbers equal or greater than 1.75, the drag force is given by

(12)

For the flow regimes with Mach number between 1 and 1.75, a linear interpolation may be used. Carlson and Hoglund (1964) proposed the following expression:

(13)

Droplets

For drag force for liquid droplets at small Reynolds numbers is given as

(14)
where the superscripts f and p refer to the continuous fluid and discrete particles (droplets, bubbles), respectively.



Dr. Goodarz Ahmadi | Turbulence & Multiphase Fluid Flow Laboratory | Department of Mechanical & Aeronautical Engineering
Copyright © 2002-2005 Dr. Goodarz Ahmadi. All rights reserved.
Potsdam, New York, 13699
ahmadi@clarkson.edu