{"id":41024,"date":"2020-02-18T09:19:12","date_gmt":"2020-02-18T09:19:12","guid":{"rendered":"\/forum\/forums\/topic\/transient-flow-through-pipe-outlet-temperature\/"},"modified":"2020-02-18T09:19:12","modified_gmt":"2020-02-18T09:19:12","slug":"transient-flow-through-pipe-outlet-temperature","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/transient-flow-through-pipe-outlet-temperature\/","title":{"rendered":"Transient flow through pipe outlet temperature"},"content":{"rendered":"

Hi<\/p>\n

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I am building a transient flow model. Flow flows through a pipe and i am trying to calculate the temperature at the outlet. <\/p>\n

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I have attached my workbench project file here. There are two projects in the workbench please refer to the project named ‘This one’.<\/p>\n

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Here it’s what I have done and the problem i am facing.<\/p>\n

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Below is the 2D planer model i built. Bottom is solid which has initial temperature of 312K and above is flow zone which has initial temperature of 300K. it’s length is 100mm.<\/p>\n

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This is mesh. along the length the numeber of division is 1000. height is divided into 100 element for each solid and fluid part.<\/p>\n

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 <\/p>\n

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And for calculation:<\/p>\n

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Energy model is on.<\/p>\n

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boundary condition is presented as below. inlet is left end of the flow zone and outlet is the right end of the flow zone.<\/p>\n

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this is scheme code for the boundary assignment:<\/p>\n

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                         (ti-menu-load-string “define\/boundary-conditions\/zone-type 8 pressure-outlet”)<\/p>\n

<\/p>\n

  (ti-menu-load-string “define\/boundary-conditions pressure-outlet 8 yes no 0 no 297.5 no yes yes no no”)<\/p>\n

<\/p>\n

  (ti-menu-load-string “define\/boundary-conditions\/zone-type 7 velocity-inlet”)<\/p>\n

<\/p>\n

  (ti-menu-load-string “define\/boundary-conditions velocity-inlet 7 yes yes no -0.1 no 0 no 1 no 0 no 310”)<\/p>\n

<\/p>\n

  (ti-menu-load-string “define\/boundary-conditions\/solid 3 no no no no no 0 no 0 no no”)<\/p>\n

<\/p>\n

                         (ti-menu-load-string “define\/boundary-conditions wall 10 0 no 0 no yes coupled no 1”)<\/p>\n

<\/p>\n

\"\"<\/p>\n

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This is how details of outlet temperature plot<\/p>\n

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area weighted average at the outlet boundary.<\/p>\n

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Along the flow direction, the minimum size of mesh is 0.1mm and the flow velocity is 0.1m\/s. so the time step size is 0.001.<\/p>\n

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I applied initilization patch on the solid so its initial temperature to be 312. and the fluid temperature is 300. The inflow temperature is 297.5.<\/p>\n

The result show as presented below:\"\"<\/p>\n

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The temperature gradually increases but at around 0.0075 and 0.0085, the red line makes two horizontal lines which represent constant temperature at those two time slots.<\/p>\n

This is my residual plot<\/p>\n

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\"\"<\/p>\n

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Why does the temperature line does not increase gradually but make two flat sections?. I have looked a the temperature value at the time step where this happens. the values gradually increases but i found for a two time steps the temperature was constant. this is shown as flat section in the plot. Is there anyone who can help with this problem?<\/p>\n

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 <\/p>\n","protected":false},"template":"","class_list":["post-41024","topic","type-topic","status-closed","hentry"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_old_topic_id":["13204"],"_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":["512"],"_bbp_subscription":["247438"],"_bbp_topic_status":["unanswered"],"_bbp_status":["publish"],"_bbp_topic_id":["41024"],"_bbp_forum_id":["27792"],"_bbp_engagement":["62","199","22555","173177"],"_bbp_voice_count":["4"],"_bbp_reply_count":["5"],"_bbp_last_reply_id":["105754"],"_bbp_last_active_id":["105754"],"_bbp_last_active_time":["2020-02-18 18:20:08"]},"test":"jhur"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/41024","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\/41024\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=41024"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}