Hello, I ran the program and found that a lot of data were 0, and the icon of mesh States was blank. Is that because the chemical reaction didn’t work? His warning is Warning 1202: The system is initiated with no particles and no solids inlet was detected.
I cannot download your zip file, please attach it again.
The warning message The system is initiated with no particles and no solids inlet was detected. is because you did not specify any solids in the Bed region. Go to Initial Condition pane, select the Bed region, go to the “bed” tab and enter a non zero solids volume fraction.
The residuals for P1, U1 and V1 are zero because these are equations that are solved in TFM, not DEM. You can remove them from the Output>Residual pan, but it doesn’t affect the solution.
The mesh is fine, you need to click on one of the variable (say aspect ratio) to see the histogram. Here you have a rectangular geometry with no cut cells so all values are the same.
Hello, I changed the solid volume fraction to 0.3 according to what you said, and then changed the temperature, because my calculation example was completed at 650℃, but it only ran for 2 seconds when it ran again, and then stopped. May I ask how to solve this, thank you
Please inspect the console messages and provide more details. There is nothing in the screenshot that points to an issue. I do not have enough resources to rerun each case that comes in.
@jeff.dietiker - The user is on the Windows platform and is getting a floating-point exception. Due to limitations of the available compiler/debugger tools available on that platform, users do not get a good stack trace when this happens. (I am working on finding a solution to this).
Running this job on Linux, I see that it’s a garden-variety zero-division error, perhaps the most common type of bug we see here on the MFiX forum:
Program terminated with signal SIGFPE, Arithmetic exception.
#0 0x00007ffa78295892 in usr_rates_des (np=1, pm=1, ijk=154, des_rates=...)
at cao-co2-dem-2d_2022-04-12T222013.031912/usr_rates_des.f:111
111 A_C=(Wads_CO2/W0_co2) * (M_CaO/M_CO2)
@wangi - you need to guard these divisions. Change
IF(X_g(IJK,CO2) > c_Limiter) then
A_C=(Wads_CO2/W0_co2) * (M_CaO/M_CO2)
ENDIF
to something like:
IF(X_g(IJK,CO2) > c_Limiter) then
if (W0_co2 .ne. 0 .and. M_CO2 .ne. 0) then
A_C=(Wads_CO2/W0_co2) * (M_CaO/M_CO2)
else
write (*,*) "W0_cO2=", W0_cO2,"M_CO2=", M_CO2
endif
end
When in doubt, print it out …
– Charles
Besides the division by zero in usr_rates_des.f, the Cp values for the solids species are ill-defined. You need to define the coefficients so Cp is non-zero for the entire temperature range of the simulation. There is an option to plot CP vs Temperature in the species popup so you can verify it it properly defined.
Hi again - here’s an update:
We have located an error in MFiX which is contributing to this problem. The high-temp Cp coefficients should not be getting used here, since THigh for the CaO species is 500. But there is a comparison in MFiX which looks wrong.
Could you help us test this? Modify the file model/thermochemical/read_thermochemical_mod.f
and change line 221 from
IF(T <= Tcom(M,N))THEN
to
IF(xT <= Tcom(M,N))THEN
then recompile the solver and try again. (You will also have to address the zero-divisions in usr_rates_des.f).
Please let us know if this helps,
– Charles
Ok, thank you for your help. As for the Cp value of Cao, I will give you a reply after running the program, thank you!
Hello, I have changed line 221 proposed before and added source file calc_force_dem.f, the following error occurs, may I ask why, thank you.
The keyword tmax sets the maximum allowable temperature. Your system has gotten to 4000K, which is very hot. If this is realistic, you can increase tmax. But there may be some problem causing this overheating (runaway reaction, etc).
The temperature is fine if I set the reaction rate to zero. It must be either the reaction rate is too high or the heat of formations are incorrect.
