{"id":460407,"date":"2026-06-26T12:15:44","date_gmt":"2026-06-26T12:15:44","guid":{"rendered":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/ddpm-ktgf-float-point-error\/"},"modified":"2026-06-26T12:15:44","modified_gmt":"2026-06-26T12:15:44","slug":"ddpm-ktgf-float-point-error","status":"publish","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/ddpm-ktgf-float-point-error\/","title":{"rendered":"DDPM-KTGF Float point error"},"content":{"rendered":"

<p>Hi everyone<\/p><p> <\/p><p>I need help with my DDPM simulation. I am Simulating a Pilot CFB BOILER using DDPM aproach, Species Transport (finite rate-eddy dissipation) with Air-wood-volatiles. The discret phase are sand (0,3mm diameter) and biomass (1 mm). My mesh have about 5 mm and minimum ortogonal quality 0,48, avg 0,95. I am using Gidaspow for drag force and non-spherical(biomass). I run the simulation in steps (cold flow, particles, energy-species equations). When simulating reactions, the continuity residuals shows higher value in beginner of each time step and  decrease over time, however, after a few time steps after (0,2-0,5s), the solver fails in one time step with Continuity, K-omega residuals. Temperature limited in all cells, turbulent viscosity ratio too. I reduced the loop-factor, I increased the lenght time factor, the number of iterations, I Reduced the URF but without sucess. If anyone knows what can be the problem, please help me.<\/p><p>Some parameters<\/p><p>First Order, transient, biomass and sand have same parameters in multiphase eulerian phase tab (Granular, gidaspow, lun, schaeffer, based ktgf)<\/p><p>DDPM – AIR-wood-volatiles – primary phase, sand and biomass discret phase<\/p><p>K-omega SST<\/p><p>Injections by surface and constant number parcell method (sand I tried 100, 50, 25 particles per parcell and biomass 1 particle per parcell)<\/p><p>Boundary conditions<\/p><p>air 4m\/s in the bottom of riser 500k<\/p><p>sand in the y tube – 0,10kg\/s (in begginer 0,15kg\/s, expected around 0,3-0,5 kg in the system) 873k<\/p><p>air 0,5m\/s in the y tube – 873k<\/p><p>biomass – 0,00055 kg\/s in the bottom of riser – 323k<\/p><p>\"\"\"\"<\/p><p> <\/p><p>\"\"\"\"<\/p><p>\"\"\"\"<\/p><p> <\/p><\/p>\n","protected":false},"template":"","class_list":["post-460407","topic","type-topic","status-publish","hentry","topic-tag-fluent-cfd-ansys-1","topic-tag-ddpm","topic-tag-fluidized-bed","topic-tag-species-reactions-2","topic-tag-transient"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_forum_id":["27792"],"_bbp_topic_id":["460407"],"_bbp_subscription":["490629","199"],"_bbp_author_ip":["163.116.233.57"],"_bbp_last_reply_id":["460425"],"_bbp_last_active_id":["460425"],"_bbp_last_active_time":["2026-06-27 01:26:13"],"_bbp_reply_count":["2"],"_bbp_reply_count_hidden":["0"],"_bbp_voice_count":["2"],"_bbp_engagement":["490629","199"],"_btv_view_count":["20"],"_bbp_topic_status":["unanswered"]},"test":"gelsonrhilgemberggmail-com"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/460407","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\/460407\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=460407"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}