{"id":394727,"date":"2024-11-21T11:01:15","date_gmt":"2024-11-21T11:01:15","guid":{"rendered":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/not-being-able-to-replicate-paper-simulations\/"},"modified":"2024-11-21T11:01:15","modified_gmt":"2024-11-21T11:01:15","slug":"not-being-able-to-replicate-paper-simulations","status":"publish","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/not-being-able-to-replicate-paper-simulations\/","title":{"rendered":"Not being able to replicate paper simulations"},"content":{"rendered":"

<p>Hi all,<\/p><p>I have been trying to reproduce the results of this paper: “Comparative analysis of hydrogen\/air combustion CFD-modeling for 3D and 2D computational domain of micro-cylindrical combustor” but I am nowhere close of getting the same results. (I’m not sure whetehr I am allowed to post the paper in here, so for now I will not do that, unless given permission).<\/p><p>The geometry is shown as follows:<\/p><p><\/p><p>For this, what is given is that this is a hydrogen-air combustion. <\/p><p>The following assumptions were given: The heat transport and body force caused by concentration gradients can be neglected due to its low value. Moreover, other assumptions are taken for CFD-modeling: steady-state conditions of combustion; no the flux of energy due to a mass concentration gradient (no Duflor effects); work by viscous forces and by pressure is not done; surface oxidation reactions of the metal wall are absent.<br>I do not think I have to adjust anything in Fluent with these assumptions.<\/p><p>It uses the Eddy Dissipation Concept model. No values were given in here, so I kept the default values.<br>The RNG k-epsilon was used, the constant values which were given here were C1 and C2, which were kept at the default values as well.<br>P1 was used for the radiation model.<br><br><\/p><p>The specific heat and density were determined by the equations of mixing-law and incompressible-ideal-gas law.<br>The viscosity is determined by Sutherland viscosity law, however, these values were not given.<br>The thermal conductivity is computed as average mass fraction of each element, I assume this could be doen with the mass weighted mixing law.<br>The pressure-based solver was used and the convergence criterion were set to the correct values as well.<\/p><p>This were the given BCs:<\/p><p><\/p><p>I ignored the excess air ratio and the H2 mass flow rate, since I was not sure where to put these.<\/p><p>I entered the mass flow rate H2+air for the mass flow rate in the inlet. I was not able to enter the N2 mass fraction, but while double checking the results, the mass fraction of this seemed correct (it probably automatically entered this after I filled in O2). For the outlet I have tried both the pressure-outlet and outlet-vent (so I was able to put the hydraulic diameters and turbulent intensity in there). It was not specifically mentioned which one was used. For the wall, steel was used and I kept everything else at its default values, since nothing was mentioned furthermore.<\/p><p> <\/p><p>For the axisymmetric simulations, these were the results:<\/p><p><\/p><p><\/p><p>Figure 1 is the paper, figure 2 is my result.<\/p><p>For some reason, in my simulation the temperature starts around 1100K, while I put 300k for the inlet. Also can be noticed that the wall temperature is much bigger and that the temperature increases very quickly from the start, compared to the paper.<\/p><p> <\/p><p>Does anyone have an idea what I am doing wrong in here?<\/p><p> <\/p><\/p>\n","protected":false},"template":"","class_list":["post-394727","topic","type-topic","status-publish","hentry","topic-tag-fluent-ansys-1","topic-tag-ansys-cfd-1","topic-tag-hydrogen-combustion","topic-tag-simulation","topic-tag-student-version"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t