{"id":45285,"date":"2020-06-19T13:14:02","date_gmt":"2020-06-19T13:14:02","guid":{"rendered":"\/forum\/forums\/topic\/aerospike-cfd-reversed-flow-on-pressure-outlet-massflow-difference-between-inlet-and-outlet\/"},"modified":"2020-06-19T13:14:02","modified_gmt":"2020-06-19T13:14:02","slug":"aerospike-cfd-reversed-flow-on-pressure-outlet-massflow-difference-between-inlet-and-outlet","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/aerospike-cfd-reversed-flow-on-pressure-outlet-massflow-difference-between-inlet-and-outlet\/","title":{"rendered":"Aerospike CFD &#8211; Reversed flow on pressure outlet\/ massflow difference between inlet and outlet"},"content":{"rendered":"<p>Hi,<\/p>\n<p><\/p>\n<p>For my thesis I have to simulate the flow in an aerospike nozzle. After some initial problems my simulation converges, in addition to the residuals I also looked at the mass flow at the inlet and outlet, but this differs considerably. The mass flow at the outlet is by a factor of 10 larger than at the inlet, additionally I often get the message during the simulation that reversed flow is present. The force on the nozzle wall is a hundred times greater then calculated. Does anybody have an idea what this could be due to?<\/p>\n<p><\/p>\n<p>I am of the opinion that my mesh is ok, because the most important key figures are kept (Max. Skewness &lt; 0.98, Min. Orth. Quality &gt; 0.1, Average Element Quality &gt; 0,775, AR &lt;5 besides some cells at the wall where the AR is up to 30). The outlet is also far enough away from the actual nozzle geometry (about 10 times the length of the nozzle)<\/p>\n<p><\/p>\n<p>I am using the following settings (on Ansys 19.2):<\/p>\n<p><\/p>\n<ul><\/p>\n<li>density based solver<\/li>\n<p><\/p>\n<li>energy equation&nbsp;<\/li>\n<p><\/p>\n<li>realizable k-epsilon<\/li>\n<p><\/p>\n<li>pressure inlet at 68,9476 bar and 2616.532 K (k = 1 and epsilon = 100 due to high turbulent viscosity)<\/li>\n<p><\/p>\n<li>pressure outlet at sea level conditions<\/li>\n<p><\/p>\n<li>All second order upwind methods&nbsp;<\/li>\n<p>\n<\/ul>\n<p><\/p>\n<p>I have also tried a massflow inlet but then the simulation didn&#8217;t converge at all. Attached are some pictures of the Mesh. If something is missing I will provide it as sonn as possible.<\/p>\n<p><\/p>\n<p>Thank you for your help.<\/p>\n<p><\/p>\n<p><img decoding=\"async\" src=\"https:\/\/us.v-cdn.net\/6032193\/uploads\/attachments\/6d6df16d-1c7d-46d8-9f59-abdf00d1f9ab\/37c71bd0-5dec-45cb-8a72-abdf00d9e169_aerospike-mesh.jpg?width=690&amp;upscale=false\" alt=\"\"><img decoding=\"async\" src=\"https:\/\/us.v-cdn.net\/6032193\/uploads\/attachments\/6d6df16d-1c7d-46d8-9f59-abdf00d1f9ab\/1a19ac69-6358-4ee9-a6ba-abdf00d9ecac_aerospike-mesh-full.jpg?width=690&amp;upscale=false\" alt=\"\"><img decoding=\"async\" src=\"https:\/\/us.v-cdn.net\/6032193\/uploads\/attachments\/6d6df16d-1c7d-46d8-9f59-abdf00d1f9ab\/2411d4f5-d98d-4233-b5b4-abdf00d9f75f_aerospike-mesh-outlet.jpg?width=690&amp;upscale=false\" alt=\"\"><img decoding=\"async\" src=\"https:\/\/us.v-cdn.net\/6032193\/uploads\/attachments\/6d6df16d-1c7d-46d8-9f59-abdf00d1f9ab\/78793827-218a-43b1-86f8-abdf00da02dc_aerospike-residuals.jpg?width=690&amp;upscale=false\" alt=\"\"><\/p>\n","protected":false},"template":"","class_list":["post-45285","topic","type-topic","status-closed","hentry"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_old_topic_id":["17466"],"_bbp_old_topic_author_name_id":["Anonymous"],"_bbp_old_is_topic_anonymous_id":["false"],"_bbp_old_closed_status_id":["publish"],"_bbp_author_ip":[null],"_bbp_old_sticky_status_id":["normal"],"_bbp_likes_count":["0"],"_btv_view_count":["628"],"_bbp_subscription":["252841"],"_bbp_topic_status":["unanswered"],"_bbp_status":["publish"],"_bbp_topic_id":["45285"],"_bbp_forum_id":["27792"],"_bbp_engagement":["118","199","178718"],"_bbp_voice_count":["3"],"_bbp_reply_count":["15"],"_bbp_last_reply_id":["120476"],"_bbp_last_active_id":["120476"],"_bbp_last_active_time":["2020-07-07 12:20:26"],"_bbp_notification_enabled":["629861"]},"test":"krux"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/45285","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\/45285\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=45285"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}