{"id":398209,"date":"2024-12-22T13:22:51","date_gmt":"2024-12-22T13:22:51","guid":{"rendered":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/udf-compiles-the-air-equation-of-state\/"},"modified":"2024-12-22T13:22:51","modified_gmt":"2024-12-22T13:22:51","slug":"udf-compiles-the-air-equation-of-state","status":"publish","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/udf-compiles-the-air-equation-of-state\/","title":{"rendered":"udf compiles the air equation of state"},"content":{"rendered":"<p>&lt;p&gt;I am using VOF to calculate two-phase flow and I need to simulate a situation where there is negative pressure in compressible liquid liquid water. After I use udf to change the equation of state of air to Tait&#8217;s equation, and derive the sound velocity equation according to Tait&#8217;s equation, both imported as compiled udf, I can&#8217;t calculate the velocity of compressible liquid liquid water over 20m\/s, where is the error that needs to be modified?&lt;\/p&gt;&lt;p&gt;Thank you.&lt;\/p&gt;&lt;p&gt;<img decoding=\"async\" src=\"https:\/\/innovationspace.ansys.com\/forum\/wp-content\/uploads\/sites\/2\/2024\/12\/22-12-2024-1734873650-mceclip0.png\" \/>&lt;\/p&gt;<\/p>\n","protected":false},"template":"","class_list":["post-398209","topic","type-topic","status-publish","hentry","topic-tag-fluent-cfd-ansys-1","topic-tag-multiphase_models-1","topic-tag-2021-r1-1","topic-tag-udf"],"aioseo_notices":[],"aioseo_head":"\n\t\t<!-- All in One SEO 4.9.10 - aioseo.com -->\n\t<meta name=\"description\" content=\"I am using VOF to calculate two-phase flow and I need to simulate a situation where there is negative pressure in compressible liquid liquid water. After I use udf to change the equation of state of air to Tait&#039;s equation, and derive the sound velocity equation according to Tait&#039;s equation, both imported as compiled udf,\" \/>\n\t<meta name=\"robots\" content=\"max-image-preview:large\" \/>\n\t<link rel=\"canonical\" href=\"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/udf-compiles-the-air-equation-of-state\/\" \/>\n\t<meta name=\"generator\" content=\"All in One SEO (AIOSEO) 4.9.10\" \/>\n\t\t<meta property=\"og:locale\" content=\"en_US\" \/>\n\t\t<meta property=\"og:site_name\" content=\"Ansys Learning Forum | Ansys Innovation Space\" \/>\n\t\t<meta property=\"og:type\" content=\"article\" \/>\n\t\t<meta property=\"og:title\" content=\"udf compiles the air equation of state | Ansys Learning Forum\" \/>\n\t\t<meta property=\"og:description\" content=\"I am using VOF to calculate two-phase flow and I need to simulate a situation where there is negative pressure in compressible liquid liquid water. After I use udf to change the equation of state of air to Tait&#039;s equation, and derive the sound velocity equation according to Tait&#039;s equation, both imported as compiled udf,\" \/>\n\t\t<meta property=\"og:url\" content=\"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/udf-compiles-the-air-equation-of-state\/\" \/>\n\t\t<meta property=\"article:published_time\" content=\"2024-12-22T13:22:51+00:00\" \/>\n\t\t<meta property=\"article:modified_time\" content=\"2024-12-22T13:22:51+00:00\" \/>\n\t\t<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n\t\t<meta name=\"twitter:title\" content=\"udf compiles the air equation of state | Ansys Learning Forum\" \/>\n\t\t<meta name=\"twitter:description\" content=\"I am using VOF to calculate two-phase flow and I need to simulate a situation where there is negative pressure in compressible liquid liquid water. After I use udf to change the equation of state of air to Tait&#039;s equation, and derive the sound velocity equation according to Tait&#039;s equation, both imported as compiled udf,\" \/>\n\t\t<script type=\"application\/ld+json\" class=\"aioseo-schema\">\n\t\t\t{\"@context\":\"https:\\\/\\\/schema.org\",\"@graph\":[{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/forums\\\/topic\\\/udf-compiles-the-air-equation-of-state\\\/#breadcrumblist\",\"itemListElement\":[{\"@type\":\"ListItem\",\"@id\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum#listItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\",\"nextItem\":{\"@type\":\"ListItem\",\"@id\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/topics\\\/#listItem\",\"name\":\"Topics\"}},{\"@type\":\"ListItem\",\"@id\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/topics\\\/#listItem\",\"position\":2,\"name\":\"Topics\",\"item\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/topics\\\/\",\"nextItem\":{\"@type\":\"ListItem\",\"@id\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/forums\\\/topic-tag\\\/udf\\\/#listItem\",\"name\":\"udf\"},\"previousItem\":{\"@type\":\"ListItem\",\"@id\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum#listItem\",\"name\":\"Home\"}},{\"@type\":\"ListItem\",\"@id\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/forums\\\/topic-tag\\\/udf\\\/#listItem\",\"position\":3,\"name\":\"udf\",\"item\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/forums\\\/topic-tag\\\/udf\\\/\",\"nextItem\":{\"@type\":\"ListItem\",\"@id\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/forums\\\/topic\\\/udf-compiles-the-air-equation-of-state\\\/#listItem\",\"name\":\"udf compiles the air equation of state\"},\"previousItem\":{\"@type\":\"ListItem\",\"@id\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/topics\\\/#listItem\",\"name\":\"Topics\"}},{\"@type\":\"ListItem\",\"@id\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/forums\\\/topic\\\/udf-compiles-the-air-equation-of-state\\\/#listItem\",\"position\":4,\"name\":\"udf compiles the air equation of state\",\"previousItem\":{\"@type\":\"ListItem\",\"@id\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/forums\\\/topic-tag\\\/udf\\\/#listItem\",\"name\":\"udf\"}}]},{\"@type\":\"Organization\",\"@id\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/#organization\",\"name\":\"Ansys Learning Forum\",\"description\":\"Ansys Innovation Space\",\"url\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/\"},{\"@type\":\"WebPage\",\"@id\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/forums\\\/topic\\\/udf-compiles-the-air-equation-of-state\\\/#webpage\",\"url\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/forums\\\/topic\\\/udf-compiles-the-air-equation-of-state\\\/\",\"name\":\"udf compiles the air equation of state | Ansys Learning Forum\",\"description\":\"I am using VOF to calculate two-phase flow and I need to simulate a situation where there is negative pressure in compressible liquid liquid water. 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