Learning Forum

[hala albukai]

a) Hi, I'm working on modeling the flow of ionic wind in air (how fast the ionized particles move) in an ionic thruster using corona discharge. I am using conservation of charge and momentum in my model. I will only consider the reactions between positive ions and neutral air particles. The magnetic force is said to be negligible and only the electrostatic force (Electric field x charge density) is taken into account as the external force per volume term in the Navier Stokes equation. I am not sure how to set the electrostatic force onto my steel electrode (emitter) of my CAD model as seen below in purple.

I need to evaluate the electric field using a UDF as the only things i know are the input voltage (40 kV) and circuit parameters of my resistor and capacitor. The charge density on the other hand, depends on the gradient of the electric potential. After some research i saw that maybe MHD model might help along with DPM injection, but i am having trouble setting it up can someone help me in more detail? What is the point of using DPM? I also read that MHD might not be built for such a project? 

b) After going through many optoins, I tried doing my model over on Maxwell but I am not sure if i can obtain my electric field values and plug it into fluent. I want that as my plan b if MHD model is unusable. Currently, i am not sure how to incorporate my resistor and capacitor into the maxwell model anyways. I only set up the materials and excitation on my emitter electrode as the input voltage and excitation on the collector electrode as ground of 0 V. In this state, my electric field is zero and does not change. I am not sure how to move forward with my problem and would appreciate the help!

[HDLI]

Hello hala albukai,

     a). In Maxwell electrostatics solver, we could use parameter> force, to get total force in the electrical field, or use filed calculator to calculate surface or volume force.

     b). I am not sure what is the application. MHD model would always use magnetic excitation in coupling between Maxwell and Flunet. Do you have the magnetic excitation? If using electical field, could you try to find Ansys EMA3D?

HDLI

[HDLI]

Hello hala albukai,

     Please see a link for MHD, ANSYS+Fluent+Magnetohydrodynamics+(MHD)+Module+Manual.pdf.

HDLI