{"id":461118,"date":"2026-07-09T09:49:12","date_gmt":"2026-07-09T09:49:12","guid":{"rendered":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/fluent-gas-outlet-and-solid-inlet-on-same-eulerian-boundary\/"},"modified":"2026-07-09T09:49:12","modified_gmt":"2026-07-09T09:49:12","slug":"fluent-gas-outlet-and-solid-inlet-on-same-eulerian-boundary","status":"publish","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/fluent-gas-outlet-and-solid-inlet-on-same-eulerian-boundary\/","title":{"rendered":"Fluent: Gas outlet and solid inlet on same Eulerian boundary"},"content":{"rendered":"

<div class=”text-base my-auto mx-auto [–thread-content-margin:var(–thread-content-margin-xs,calc(var(–spacing)*4))] @w-sm\/main:[–thread-content-margin:var(–thread-content-margin-sm,calc(var(–spacing)*6))] @w-lg\/main:[–thread-content-margin:var(–thread-content-margin-lg,calc(var(–spacing)*16))] px-(–thread-content-margin)”><div class=”[–thread-content-max-width:40rem] @w-lg\/main:[–thread-content-max-width:48rem] mx-auto max-w-(–thread-content-max-width) flex-1 group\/turn-messages focus-visible:outline-hidden relative flex w-full min-w-0 flex-col agent-turn” data-conversation-screenshot-content=””><div class=”flex max-w-full flex-col gap-4 grow”><div class=”min-h-8 text-message relative flex w-full flex-col items-end gap-2 text-start break-words whitespace-normal outline-none keyboard-focused:focus-ring [.text-message+&]:mt-1″ dir=”auto” data-message-author-role=”assistant” data-message-id=”032aac75-520d-4aa0-9439-513d25653a37″ data-message-model-slug=”gpt-5-5-thinking”><div class=”flex w-full flex-col gap-1 empty:hidden”><div class=”markdown prose dark:prose-invert wrap-break-word w-full light markdown-new-styling”><p class=”” data-start=”19″ data-end=”34″>Hello everyone,<\/p><p data-start=”36″ data-end=”181″>I am building a 2D axisymmetric CFD model of a hydrogen-based shaft furnace in ANSYS Fluent. The model is a counter-current gas-solid moving bed.<\/p><p data-start=”183″ data-end=”395″>The gas phase enters from the side\/lower reduction zone and flows upward. The solid phase, iron ore pellets, enters from the furnace top and moves downward. Therefore, the top boundary has two physical functions:<\/p><p data-start=”397″ data-end=”450″>Gas phase: top gas outlet<br data-start=”422″ data-end=”425″>Solid phase: pellet inlet<\/p><p data-start=”452″ data-end=”601″>I am using the Eulerian multiphase model with one gas phase and one granular solid phase. The pellets are treated as a pseudo-fluid \/ granular phase.<\/p><p data-start=”603″ data-end=”906″>My question is about the top boundary condition. In Fluent, one boundary zone usually has only one boundary type, such as pressure-outlet, velocity-inlet, or mass-flow-inlet. However, in my physical model, the same furnace top location should allow gas to leave the domain while solids enter the domain.<\/p><p data-start=”908″ data-end=”949″>I have considered three possible methods:<\/p><\/p>\n

    <li data-section-id=”1xtvth5″ data-start=”951″ data-end=”1147″>Split the top boundary into two adjacent zones. One zone is defined as pressure-outlet for the gas phase, and the other zone is defined as velocity-inlet or mass-flow-inlet for the solid phase.<\/li>\n

    <li data-section-id=”1iaks5f” data-start=”1149″ data-end=”1416″>Use one pressure-outlet boundary and set the backflow volume fraction of the solid phase. However, I understand that backflow settings are only used when reverse flow actually occurs at the pressure outlet, so this may not be able to force a continuous solid feed.<\/li>\n<\/ol>\n

    <p data-start=”1603″ data-end=”1620″>My questions are:<\/p><\/p>\n

      <li data-section-id=”15rbhfv” data-start=”1622″ data-end=”1749″>In the Fluent Eulerian granular model, can one boundary be used as a gas pressure outlet and a solid inlet at the same time?<\/li>\n

      <li data-section-id=”esv4c9″ data-start=”1751″ data-end=”1858″>Is it valid to use pressure-outlet plus backflow volume fraction to represent continuous pellet feeding?<\/li>\n

      <li data-section-id=”wfxooe” data-start=”1860″ data-end=”2018″>If backflow volume fraction cannot force a solid inlet, is splitting the top boundary into a gas outlet zone and a solid inlet zone the recommended method?<\/li>\n

      <li data-section-id=”1tf1qs3″ data-start=”2020″ data-end=”2152″>For a counter-current gas-solid moving bed or shaft furnace model, what is the best practice for this type of boundary condition?<\/li>\n

      <li data-section-id=”1gn9rmm” data-start=”2154″ data-end=”2276″>Are there any Fluent tutorials or examples involving gas outlet and solid inlet at the same physical boundary location?<\/li>\n<\/ol>\n

      <p data-start=”2278″ data-end=”2323″>Any suggestions would be greatly appreciated.<\/p><p data-start=”2325″ data-end=”2345″ data-is-last-node=”” data-is-only-node=””>Thank you very much.<\/p><\/div><\/div><\/div><\/div><div class=”z-0 flex min-h-[46px] justify-start”> <\/div><\/div><\/div><\/p>\n","protected":false},"template":"","class_list":["post-461118","topic","type-topic","status-publish","hentry"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_forum_id":["27792"],"_bbp_topic_id":["461118"],"_bbp_subscription":["512399","199"],"_bbp_author_ip":["61.93.255.62"],"_bbp_last_reply_id":["461125"],"_bbp_last_active_id":["461125"],"_bbp_last_active_time":["2026-07-09 10:26:24"],"_bbp_reply_count":["2"],"_bbp_reply_count_hidden":["0"],"_bbp_voice_count":["2"],"_bbp_engagement":["512399","199"],"_btv_view_count":["46"],"_bbp_topic_status":["unanswered"],"_bbp_likes_count":["1"]},"test":"2247269037qq-com"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/461118","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\/461118\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=461118"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}