{"id":43507,"date":"2020-05-02T00:01:07","date_gmt":"2020-05-02T00:01:07","guid":{"rendered":"\/forum\/forums\/topic\/free-surface-oscillation-jump-near-inlet-using-vof\/"},"modified":"2020-05-02T00:01:07","modified_gmt":"2020-05-02T00:01:07","slug":"free-surface-oscillation-jump-near-inlet-using-vof","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/free-surface-oscillation-jump-near-inlet-using-vof\/","title":{"rendered":"Free surface oscillation\/jump near inlet using VOF"},"content":{"rendered":"<p>We are using VOF model to simulate a river water flow over the&nbsp;water bed and also with a small<br \/>\npit&nbsp;(fish nest) in the middle of the no-slip bottom wall. Our flow&nbsp;domain has a very small tilt, with a<br \/>\n3rd or a 4th decimal numbered slope.<br \/>\n&nbsp;<br \/>\nThe&nbsp;boundary&nbsp;conditions are as shown in the schematic. Mass flow inlet or velocity profile inlet<br \/>\npressure outlet&nbsp;(hydrostatic&nbsp;pressure profile), bottom No-slip wall and the top boundary is symmetry.<br \/>\nFor such a&nbsp;simulation case, we&nbsp;are observing a few millimeters to centimeters unphysical jumps and<br \/>\noscillations&nbsp;in the free&nbsp;surface near the inlet&nbsp;above the water depth we specified. These<br \/>\njumps\/oscillations&nbsp;gradually settle down further downstream. Below is a free surface plot, for a<br \/>\ndomain with a pit on the water bed from 10 to 14 horizontal distance.&nbsp; This issue is there for either<br \/>\nmass flow inlet or velocity profile inlet boundary conditions.&nbsp; Note that the open channel flow<br \/>\nmodel&nbsp;doesn&#8217;t work for our case as we are investigating the effect of slope and other parameters<br \/>\neffect but&nbsp;FLUENT open channel flow model enforces the gravity is always normal to the free<br \/>\nsurface.<br \/>\n<img decoding=\"async\" src=\"https:\/\/us.v-cdn.net\/6032193\/uploads\/attachments\/b834734a-7ad6-4c80-a4c9-a97a017bc129\/d975c6cd-6eb5-49ba-ae92-abae018a85bb_approach-sketch.jpg?width=690&amp;upscale=false\" alt=\"\"><br \/>\n<img decoding=\"async\" src=\"https:\/\/us.v-cdn.net\/6032193\/uploads\/attachments\/b834734a-7ad6-4c80-a4c9-a97a017bc129\/c6507ebf-b80b-45ec-9d79-abae018a95e2_free-surface-profile.jpg?width=690&amp;upscale=false\" alt=\"\"><\/p>\n","protected":false},"template":"","class_list":["post-43507","topic","type-topic","status-closed","hentry"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_old_topic_id":["15688"],"_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":["929"],"_bbp_subscription":["237403"],"_bbp_topic_status":["unanswered"],"_bbp_status":["publish"],"_bbp_topic_id":["43507"],"_bbp_forum_id":["27792"],"_bbp_engagement":["25","4948","159560"],"_bbp_voice_count":["3"],"_bbp_reply_count":["5"],"_bbp_last_reply_id":["114267"],"_bbp_last_active_id":["114267"],"_bbp_last_active_time":["2020-05-12 23:52:52"]},"test":"xinguidaho-edu"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/43507","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\/43507\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=43507"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}