Aerosol Research

Our aerosol and particles research covers diverse area.  We have worked on

1. acoustic agglomeration of particles.

2. electro-coalescence of aerosols

3. sectional and quadrature method of moments solutions of the General Dynamic Equation

Acoustic Agglomeration

Acoustic agglomeration refers to the enhanced aerosol agglomeration process that occurs in acoustic fields.  In  Ezekoye and Wibowo “Simulation of Acoustic Agglomeration Processes using a Sectional Algorithm,  J. of Aerosol Sci., vol. 30. 1999, we  examine the various theoretical descriptions of acoustic agglomeration kernels.

Electro-coalescence

Aerosol particles will experience enhanced agglomeration dynamics when subjected to large electric fields.  We have examined these dynamics experimentally and computationally.

We performed laser extinction measurements in a unit aerosol reactor in which a strong electric field was imposed.

As the applied voltage increases the sedimentation time decreases.

Sectional computation show similar dynamics.

General Dynamic Equation Solutions

There are  many physical processes involved in aerosol formation and growth.  These include:

• Homogeneous nucleation : Formation of critical sized clusters of particles from a condensable species.

• Surface growth : Growth of critical sized clusters due to addition of molecules.

• Coagulation : Gain and loss of particles of a particular size due to collisions with all other particles.

• Particle diffusion and thermophoresis.
   

The evolution of an aerosol distribution in non-uniform temperature and flow fields requires solution of the GDE at each point in space.  There is a need to formulate aerosol  problems such that the GDE is of the same form as the other transport equations.

A convenient form for describing the aerosol distribution is by using moments of the size distribution function.  Based on these moments, we can generate a moment evolution equation.

The moment evolution equation becomes:

There is still a problem with this general form.  We can't close the problem since we have integrals of functionals which we can't evaluate simply in terms of moments.  The solution rests in the quadrature method of moments.

We use quadrature points and weights to evaluate and close the moment form of the equations.  For a simple pipe flow reactor, we are able to calculate various moments of the evolving particle distribution for a multi-physics growth process.

Number Concentration	Average Particle Diameter

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