# Unable to select created Internal Flow Volume for material assignment **URL:** \ **Category:** Project Support\ **Created:** [October 21, 2025, 7:02pm UTC](https://www.simscale.com/forum/t/unable-to-select-created-internal-flow-volume-for-material-assignment/100481 "2025-10-21T19:02:15Z")\ **Posts on this page:** 1\ **Showing post:** 2
**Author:** ![nelta](https://www.simscale.com/forum/letter_avatar/nelta/32/6_22734026db12803ebb3e059622ac3534.png) [@nelta](https://www.simscale.com/forum/u/nelta)\ **Post date:** [October 22, 2025, 7:21pm UTC](https://www.simscale.com/forum/t/unable-to-select-created-internal-flow-volume-for-material-assignment/100481/2 "2025-10-22T19:21:47Z")
Perhaps, seeing the project will be helpful. Here is a previous post from the forum on how to share a project: > [@Guide to Clear and Understandable Forum Posting](https://www.simscale.com/forum/t/guide-to-clear-and-understandable-forum-posting/99461): > > Hi SimScale Community! wave We in the Support Team have noticed that some users are unsure about what to include in their forum posts to get quick and effective help. Let’s make the process smoother! Here are three essential tips for crafting a successful forum post: 1. Describe Your Problem Clearly Keep it concise! A brief overview of your project’s goal, setup, and the specific issue is usually sufficient. If more details are needed, we’ll ask for clarification. This helps us understand y… Also, perhaps the internal flow volume was not created successfully. When selecting the seed face, select any internal face that will be in contact with the flow region. When selecting the boundary face, ensure that there is a distinction or a clear boundary between the internal and external domains. In other words, to select the boundary face select the faces that lie between the external environment and the internal. Follow along [this](https://www.simscale.com/docs/tutorials/tutorial-fluid-flow-through-a-valve/) tutorial for more information. --- _[View the full topic](https://www.simscale.com/forum/t/unable-to-select-created-internal-flow-volume-for-material-assignment/100481)._