# Non-Newtonian viscosity model **URL:** \ **Category:** Project Support\ **Created:** [January 23, 2026, 10:01am UTC](https://www.simscale.com/forum/t/non-newtonian-viscosity-model/100699 "2026-01-23T10:01:14Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![veryms](https://www.simscale.com/forum/letter_avatar/veryms/32/5_5575768a8748004e209b776fc1b2916d.png) [@veryms](https://www.simscale.com/forum/u/veryms)\ **Post date:** [January 23, 2026, 10:01am UTC](https://www.simscale.com/forum/t/non-newtonian-viscosity-model/100699/1 "2026-01-23T10:01:14Z")
Hi everyone. I’m running a CFD simulation of a membrane oxygenator. For that, I need blood, which is a non-newtonian Herschel-Bulkley fluid. I am using incompressible, laminar flow. When I try to change the viscosity model newtonian to something else, it doesn’t let me. As in, it literally just, doesn’t have the drop down. I duplicated water. Below is an image, and when I click on any of them, nothing happens at all: ![image](https://www.simscale.com/forum/uploads/default/original/3X/9/5/9575793bf7bd88e3e4629af4d28e255ebd7a20c1.png) Does anyone know why? ---
**Author:** ![Ricardopg](https://www.simscale.com/forum/user_avatar/www.simscale.com/ricardopg/32/26909_2.png) [@Ricardopg](https://www.simscale.com/forum/u/Ricardopg)\ **Post date:** [January 23, 2026, 12:49pm UTC](https://www.simscale.com/forum/t/non-newtonian-viscosity-model/100699/2 "2026-01-23T12:49:09Z")
Hi, First create the material, then change the settings: ![image](https://www.simscale.com/forum/uploads/default/original/3X/8/f/8f6ab55d751ae0dd3f1d4cca912f51022d8b3600.png) ---
**Author:** ![veryms](https://www.simscale.com/forum/letter_avatar/veryms/32/5_5575768a8748004e209b776fc1b2916d.png) [@veryms](https://www.simscale.com/forum/u/veryms)\ **Post date:** [January 23, 2026, 4:37pm UTC](https://www.simscale.com/forum/t/non-newtonian-viscosity-model/100699/3 "2026-01-23T16:37:03Z")
Okay, thank you so much.