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## Error

• ### Heat flux needed

Hello!

I need to asses the power (W/m2) entering an concrete structure from the ground surrounding it. But I don't know exactly which of the rate resulted I need to check. Using masking domain (Subdomain Boundary Rate Budget) is it the correct way of assessing it (see the picture)?

I am studying moulded walls equipped with pipes through which a fluid circulates in order to transform the moulded walls into heat exchangers that supply a heat pump. The pipes are caught to the reinforcement cage. However, in the numerical model, I replace the physical pipes with nodes acting like a source or sink of heat. The power set at the nodes represents the power demand during a season (by example 5 W/node in the hottest day of summer). I need to find out how much of the energy can be exchanged with the ground and how much of it is lost within the concrete and the excavation.
• ### Re: Dispersivity

I understand, I hope, how the software calculates the conductivity after modeling two simple models. My conclusions are: Solid thermal conductivity = Bulk thermal conductivity when water is not present in the layer and Solid thermal conductivity together with fluid thermal conductivity = Bulk thermal conductivity when layer is saturated. The formula used is the empirical one: n*lambdafluid + (1-n)*lambdasolid = lambda bulk. Am I right? Thank you!
• ### Re: Dispersivity

Thank you!

I don't find anything clear about this parameter. Also, I don't clearly understand how heat conductivity along with volumetric heat capacity is calculated based on porosity and fluid/solid properties. I will do some simple models to better understand the last two terms. Please, help me if you have an answer at hand. Thank you in advance!
• ### Dispersivity

Hello! How do you usually consider longitudinal/tranverse dispersivity values for heat transfer? Default, 0 or different?

When I use a simple model to see the influence of this parameter I observe huge differences in temperature field. The material I used is concrete, therefore I firstly set dispersivity to 0 in the first case (full homogenius) followed by setting default values (5m/0.5m) in the second case. The results are in the attached image.

There is any table showing the most correct values to consider based on different criteria?

Thank you!

• ### Divergence of the flux by conduction and by advection

Hello, again!

I need to find out the divergence [W/m3] of the flux by conduction and advection from FEFLOW. There is any way for finding them? Actually I don't really understand where should I look to find heat flow [W/m2] by conduction and advection followed by finding out their divergence. Maybe you can help me with this one.

Thank you!
• ### Re: Invalid mesh topology

I managed to succeed by using Triangle along with points. There is need for setting small point target size with a small graduation not distort the straight lines representing the walls contour. The nodes can be furthermore connected with lines, for an easily find the center point.
• ### Re: Invalid mesh topology

The main idea is that I need a certain distance between the node in all three directions. For example If I model a diaphragm wall having 6m length, 1.2m wide and 15m depth, I need to have nodes at 10cm from the edges, at 1m distance on one face and also at every meter in depth.

For example, in the image below, W - 1.2m, L - 6m, sp - 1m, c - 0.1m, D - 15m. I solve depth by defining slices, but what about the others?

Thank you!
• ### Re: Invalid mesh topology

This is the image.
• ### Re: Invalid mesh topology

Sorry If I don't get it, but do you mean like in the image below?

I made the lines using short lines of 1 meter. On the left side is before while on the right side is after I connect the dots. Even like this, it doesn't work.

Only when I draw connection lines without using the dots, by mouse clicking, then it works. I will ad the image on next one. Another way is to find a good refinement of the lines to obtain nodes at each 0.25 or 0.5 m, but it's not perfect.
• ### Invalid mesh topology

Hello. In my model I need to set nodes at a certain distance. May I do this using meshing? I didn't find any solution for this using meshing therefore I tried to draw lines which intersections would represent the nodes I need. The problem is that when I am using "F2" key to define lines coordinates, FEFLOW crashes at meshing, using Grid Builder method. When I add lines using mouse click, it works. I saw that this topic was posted 5 years ago, but no solution was found. There is any way I can obtain a certain distance between nodes, rather than using lines?

Also, Triangle and Advance Front are not helping me if Grid Builder doesn't work, or maybe I don't know how to use them.

Thank you!