{"id":435993,"date":"2025-07-03T12:16:31","date_gmt":"2025-07-03T12:16:31","guid":{"rendered":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/suction-lift-time-analysis\/"},"modified":"2025-07-03T12:16:31","modified_gmt":"2025-07-03T12:16:31","slug":"suction-lift-time-analysis","status":"publish","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/suction-lift-time-analysis\/","title":{"rendered":"SUCTION LIFT TIME ANALYSIS"},"content":{"rendered":"<p>&lt;div dir=&#8221;auto&#8221;&gt;hELLO THERE. Kindly help me out. Im modelling the suction operationality of a pump connected to a pipe with pressure inlet at the pipe start(sump).&nbsp;&lt;\/div&gt;&lt;div dir=&#8221;auto&#8221;&gt;<img decoding=\"async\" src=\"https:\/\/innovationspace.ansys.com\/forum\/wp-content\/uploads\/sites\/2\/2025\/07\/02-07-2025-1751464657-mceclip0.png\" \/><img decoding=\"async\" src=\"https:\/\/innovationspace.ansys.com\/forum\/wp-content\/uploads\/sites\/2\/2025\/07\/02-07-2025-1751464770-mceclip1.png\" \/>&lt;\/div&gt;&lt;div dir=&#8221;auto&#8221;&gt;The impeller starts rotating, this creates suction and less pressure and on the other side of the nrv is pipe which is connected to the sump (inlet), this is at atmosphere pressure. This pressure difference shall open up the nrv gradually and them the water starts rising from the sump replacing the air in the pipe. Without the nrv open, the water wouldn&#8217;t lift up(right?)&lt;\/div&gt;&lt;div dir=&#8221;auto&#8221;&gt;Now to model the nrv behaviour, I specified a small zone near pump inlet as porous media zone with a high viscous resistance and thought that I will decrease this gradually (letting more flow in) as the pressure difference rises. All good. But as soon I start the simulation, fluent reports negative absolute pressure all inside the pump.&lt;\/div&gt;&lt;div dir=&#8221;auto&#8221;&gt;&nbsp;&lt;\/div&gt;&lt;div dir=&#8221;auto&#8221;&gt;I want a realistic behaviour wherein pressure drops inside pump. Nrv opens up. Water rises from sump displacing the air inside the pump. And I just want to know the time It&#8217;d take the water to each the pump inlet.&nbsp;&lt;\/div&gt;&lt;div dir=&#8221;auto&#8221;&gt;Please guide me&lt;\/div&gt;<\/p>\n","protected":false},"template":"","class_list":["post-435993","topic","type-topic","status-publish","hentry","topic-tag-fluent-ansys-1","topic-tag-fluent-cfd-ansys-1","topic-tag-ForumCoordinator-1","topic-tag-multiphase_models-1","topic-tag-centrifugal-pump","topic-tag-fluent-mesh","topic-tag-mrf","topic-tag-mrf-frozen-rotor","topic-tag-sliding-mesh"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_forum_id":["27792"],"_bbp_topic_id":["435993"],"_bbp_subscription":["482699","5978"],"_bbp_author_ip":["121.240.235.170"],"_bbp_last_reply_id":["437401"],"_bbp_last_active_id":["437401"],"_bbp_last_active_time":["2025-07-22 07:28:36"],"_bbp_reply_count":["12"],"_bbp_reply_count_hidden":["0"],"_bbp_voice_count":["2"],"_bbp_engagement":["482699","5978"],"_btv_view_count":["213"],"_bbp_topic_status":["unanswered"],"_bbp_likes_count":["1"],"_edit_lock":["1751545031:482699"]},"test":"msm19b039iiitdm-ac-in"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/435993","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\/435993\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=435993"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}