{"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>&lt;p&gt;Hi all,&lt;\/p&gt;&lt;p&gt;I have been trying to reproduce the results of this paper: &#8220;Comparative analysis of hydrogen\/air combustion&nbsp;CFD-modeling for 3D and 2D computational&nbsp;domain of micro-cylindrical combustor&#8221; but I am nowhere close of getting the same results. (I&#8217;m not sure whetehr I am allowed to post the paper in here, so for now I will not do that, unless given permission).&lt;\/p&gt;&lt;p&gt;The geometry is shown as follows:&lt;\/p&gt;&lt;p&gt;<img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/innovationspace.ansys.com\/forum\/wp-content\/uploads\/sites\/2\/2024\/11\/21-11-2024-1732186156-mceclip0.png\" width=\"792\" height=\"246\" \/>&lt;\/p&gt;&lt;p&gt;For this, what is given is that this is a hydrogen-air combustion.&nbsp;&lt;\/p&gt;&lt;p&gt;The following assumptions were given: The heat transport and&nbsp;body force caused by concentration gradients can be neglected due to its low value. Moreover, other assumptions are&nbsp;taken for CFD-modeling: steady-state conditions of combustion; no the flux of energy due to a mass concentration&nbsp;gradient (no Duflor effects); work by viscous forces and by&nbsp;pressure is not done; surface oxidation reactions of the metal&nbsp;wall are absent.&lt;br&gt;I do not think I have to adjust anything in Fluent with these assumptions.&lt;\/p&gt;&lt;p&gt;It uses the Eddy Dissipation Concept model. No values were given in here, so I kept the default values.&lt;br&gt;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.&lt;br&gt;P1 was used for the radiation model.&lt;br&gt;&lt;br&gt;&lt;\/p&gt;&lt;p&gt;The specific heat and density were determined by the equations of mixing-law and&nbsp;incompressible-ideal-gas law.&lt;br&gt;The viscosity is determined by Sutherland viscosity law, however, these values were not given.&lt;br&gt;The&nbsp;thermal conductivity is computed as average&nbsp;mass fraction of each element, I assume this could be doen with the mass weighted mixing law.&lt;br&gt;The pressure-based solver was used and the convergence criterion were set to the correct values as well.&lt;\/p&gt;&lt;p&gt;This were the given BCs:&lt;\/p&gt;&lt;p&gt;<img decoding=\"async\" src=\"https:\/\/innovationspace.ansys.com\/forum\/wp-content\/uploads\/sites\/2\/2024\/11\/21-11-2024-1732186558-mceclip1.png\" \/>&lt;\/p&gt;&lt;p&gt;I ignored the excess air ratio and the H2 mass flow rate, since I was not sure where to put these.&lt;\/p&gt;&lt;p&gt;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.&lt;\/p&gt;&lt;p&gt;&nbsp;&lt;\/p&gt;&lt;p&gt;For the axisymmetric simulations, these were the results:&lt;\/p&gt;&lt;p&gt;<img decoding=\"async\" src=\"https:\/\/innovationspace.ansys.com\/forum\/wp-content\/uploads\/sites\/2\/2024\/11\/21-11-2024-1732186671-mceclip2.png\" \/>&lt;\/p&gt;&lt;p&gt;<img decoding=\"async\" src=\"https:\/\/innovationspace.ansys.com\/forum\/wp-content\/uploads\/sites\/2\/2024\/11\/21-11-2024-1732186676-mceclip3.png\" \/>&lt;\/p&gt;&lt;p&gt;Figure 1 is the paper, figure 2 is my result.&lt;\/p&gt;&lt;p&gt;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.&lt;\/p&gt;&lt;p&gt;&nbsp;&lt;\/p&gt;&lt;p&gt;Does anyone have an idea what I am doing wrong in here?&lt;\/p&gt;&lt;p&gt;&nbsp;&lt;\/p&gt;<\/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":[],"acf":[],"custom_fields":[{"0":{"_bbp_subscription":["483923","199","14415","33091"],"_bbp_author_ip":["131.155.9.104"],"_btv_view_count":["406"],"_bbp_topic_status":["unanswered"],"_edit_lock":["1732186947:483923"],"_bbp_topic_id":["394727"],"_bbp_forum_id":["27792"],"_bbp_engagement":["199","14415","483923","33091"],"_bbp_voice_count":["4"],"_bbp_reply_count":["20"],"_bbp_last_reply_id":["397946"],"_bbp_last_active_id":["397946"],"_bbp_last_active_time":["2024-12-19 05:14:12"]},"test":"m-t-vustudent-tue-nl"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/394727","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics"}],"about":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/types\/topic"}],"version-history":[{"count":0,"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/394727\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=394727"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}