Data at every node point

MFiX How to
#1

Dear Expert,
I want to know how I can get the data at every node point during the simulation with respect to time. Suppose I want to save the data point at every node point and (x,y,z coordinate) of velocity, pressure, and volume fraction. I do not understand how I can save it. please let me know how I can get this data.

#2

Please see the section postprocessing in the MFiX manual.

You can use either vtu/vtp files which can be examined with Paraview or custom Python code, or the older SPX file format, which can be examined with postmfix

#3

Dear cgw,
As per the mfix manual, I save the data on each time step (0.05 sec) in VTK file format, I can also change the time step to very low like 0.001 s but the value stored in each time step is not in the node value. Please check the picture I saved from Mfix. I also attached the picture of what I want. Suppose if total node point is 6000 then every time total value is saved in 6000 nodes.
Mfix_Data [Mfix]
node_Data [That I want]

#4

The data saved in the vtu files is cell data, i.e. one value per cell. For scalar quantities (pressure, temperature) this is located at the cell center. For velocity, each component is stored at the face center (east face for u, north cell for v and bottom cell for w).

I am not sure what steps you took to display the MFiX table above, but this is not the data stored into a single vtu file. Did you apply a “plot selection over time” filter or some other filter?

Now, if you have a rectangular geometry with 6000 cells and the vtu region encompasses the entire domain, you should get 6000 values per variable in the vtu file. If you use cut-cells and you have inactive cells, you will get fewer cells than that, based on the number of active fluid cells. If your vtk region is smaller than the entire domain, you will also get fewer cells.

#5

Dear Jeff,
I checked the data point at each cell on the ParaView but this is the single data set for the particular time step like 20 sec. If I want to save the every sec data set at each cell up to 20-sec then we want 20 data set files. could you tell me how can i get every time step file for each cell?

any other way in the mfix to save the data set at every time step on each cell during the simulation?

#6

Sorry I don’t understand. Do you want to save the vtk data every 1 second of simulation or at every time step?

You can control how often the data is saved by setting the write interval for each vtk file (vtk_dt). For example if you set vtk_dt=1.0 then the data will be saved every 1 second of simulation time. You will get 21 files over a 20-sec simulation (time=0, 1, 2 … 20 seconds).

#7

I write a 0.01-time interval for each (vtk_dt) so the total saved file is 2000 vtu. then, if I want to extract the data point at every cell in the particular time step, I have to upload the same time step (.vtu) file in the postprocessing software (paraview), and then we can extract the data. AM I write?
I saw the particle time step data in the paraview then i get the data point in the some cell.

#8

When you say you want to extract the data point at every cell, what exactly do you want to do? Save in into another format, i.e. export it?

#9

I attached the file as I wanted. This is the one-time step file, and I record at 0.01 sec including the X coordinate, Y coordinate, volume fraction, and velocity value. I want to record these data set in as desired time step during the simulation in the csv or xls formate. it is possible to extract these types of data in the mfix.
data.zip (313.4 KB)

#10

Dear expert,
Can I save these type of data set at every node during the simualtion at every time setp or we have to create manually from the other process.