{"id":357825,"date":"2024-03-19T08:42:16","date_gmt":"2024-03-19T08:42:16","guid":{"rendered":"\/forum\/?post_type=topic&p=357825"},"modified":"2024-03-23T01:33:25","modified_gmt":"2024-03-23T01:33:25","slug":"unresonable-result-when-using-polynomial-fitting-properties","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/unresonable-result-when-using-polynomial-fitting-properties\/","title":{"rendered":"unresonable result when using polynomial fitting properties"},"content":{"rendered":"

Hello everyonr,<\/p>\n

I’m simulating a steady internal cylindrical pipe flow of water with constant heat flux on the wall. I have exported water thermal properties and fit them using polynomial ranging from 280\u2103 to 373\u2103 in Origin.  Four properties are all fitting using polynomial.<\/p>\n

<\/p>\n

But the curve is totally different from origin one in same range as showing below. Let’s take Cp for an example.<\/p>\n

<\/p>\n

<\/p>\n

And after I run my simulation and it converged. I checked the density contour. The ranging density is unreasonably higher than that in ordinary temperature. It’s weird that water is heated and its density is supposed to decrease when fluid temperature is increasing. The density contour is shown below.<\/p>\n

<\/p>\n

Same problems as Cp. Maximum Cp is far more lower than minimum value of the fitting curve.<\/p>\n

<\/p>\n

It almost drives me mad these days. I have try different ways to apply polynomial fitting function like expression and UDF.But it seems that the outcome is almost the same.<\/p>\n

Anyone could help explain it and how do you guys apply polynomial properties in Fluent?<\/p>\n

Regards.<\/p>\n","protected":false},"template":"","class_list":["post-357825","topic","type-topic","status-closed","hentry","topic-tag-fluent","topic-tag-fluid-volume","topic-tag-piece-wise-polynomials"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t