The role of the electric body force in the generation of secondary flows and turbulence in precipitators is poorly understood at present, despite the fact that these disturbances are thought to be detrimental to precipitator performance. This paper undertakes a fundamental analysis of the problem using the Navier-Stokes and reduced Maxwell equations. It is shown that the rotational component of the current density causes vorticity production in the gas, and is therefore the source of secondary flows and turbulence. When the current density is irrotational, the electric body force causes a change in the pressure distribution but has no effect on the velocity field. Since the current density distribution is determined by the electrode geometry alone, the electrodes should be designed to minimize the rotational component of the current density and thus reduce gas flow disturbances.
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The support of the U.S. Environmental Protection Agency through grant R809727-01 is gratefully acknowledged.