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Creating and implementing UDF for DPM droplet evaporation rate |
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September 10, 2023, 05:39 |
Creating and implementing UDF for DPM droplet evaporation rate
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Join Date: Aug 2023
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Hi,
I am trying to simulate a flash atomizing water spray. I've read that the 'pressure boiling' and 'temperature dependent latent heat' models do not calculate an appropriately fast evaporation rate and I will need to use a UDF. I am currently doing a steady sim with interaction with continuous phase turned on. I have never used UDF's (or have programming experience beyond matlab) and don't know where/how to start. This is the calculation process (see below) I essentially need to follow (the code is written in Matlab, and I have all the parameters except for each droplet diameter, which I need to take from ansys at each iteration to get the new mass transfer rate (which is the mass removed from the droplet and added as a eulerian vapor phase). Any help as to how I would turn this into a UDF would be much appreciated. Thanks %% flashing mdot component % get surface area of particle using diameter provided by ansys D = D_p; % FROM ANSYS A_p = 4*pi*(D/2)^2; % using thermo constants and calculated alpha, along with surface % area calculate mass transfer from flashing mdot_flash = alpha * A_p * (TSH_act) / liq.hv; %% condensing mdot component % calculate Re with that D Re_star = liq.rho*u_rel_initial*D/mu_ref; % calculate Pr with known values Pr_star = mu_ref*cp_ref/k_ref; % calculate Nu* using Frossling correlation Nu_star = 2 + 0.552 * Re_star^0.5 * Pr_star^(1/3); % solve via netwon raphson % error tolerance err = 1e-20; % initial guess mdot_cond = 1; % initial diff diff = 1; % loop until converged mdot_cond while diff > err % coefficient for equation using fluent droplet diameterend %% total mRES = mdot_cond + mdot_flash; |
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dpm, evaporation, flashing flow, udf |
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