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December 12, 2016, 08:21 
Help in Fluent DPM .....

#1 
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Aarthy Meena
Join Date: Oct 2015
Location: Trichy
Posts: 29
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Help in Fluent DPM……
I am simulating nanofluid flow over a circular cylinder in a rectangular domain. The diameter of the hot circular cylinder is 1mm, length of the flow domain is 100mm and the height is 60mm. The cylinder is maintained at 310K while the inlet fluid temperature is 300K. I am using Fluent DPM and hence, the thickness of the domain is taken as 30nm which is equal to the diameter of the nanoparticle. The flow is steady at Re = 10 (velocity = 0.146m/s) and steady particle tracking is used. Group injection (10000 parcels) with constant particle diameter (30 nm) is used. I am having doubts in determining the mass flow rate to be entered in Injection > point properties. I have tried two methods to calculate the mass flow rate Method 1 Volume fraction = (number of nanoparticles x volume of a single nanoparticle) / Volume of domain i.e Volume fraction = Total volume of all nanoparticles / volume of domain In our case 0.05 (5% volume fraction) = Total volume of all nanoparticles / 100mm x 60 mm x 30nm Which gives volume of nanoparticles = 9 x 1012m3 Mass flow rate = 9 x 1012 x 3690 (Density of nanoparticle) = 3.321 x 108 kg/s As there are 10000 parcels, mass flow rate of a single parcel = 3.321 x 108 / 10000 = 3.321x1012 kg/s Method 2 Volume flow rate at the inlet = velocity x cross sectional area = 0.146 (velocity) x 60 x 103 x 30 x 109 = 2.628 x 1010mm3/s 5 % of the volume flow rate = 0.05 x 2.628 x 1010 = 1.314 x 1011 m3/s Corresponding mass flow rate = 1.314 x 1011 x 3690 (density) Mass flow rate of single parcel = (1.314 x 1011 x 3690) / 10000 = 4.8486x1012kg/s While following both the methods, I am able to get reasonable particle tracks. But, when I plot contours > Discrete phase variables > DPM volume fraction. I am getting unreasonable values in the order of 1e10 which is actually expected to be in the range of 0.05. Moreover, there is no change in mean Nusselt number. It is same as that observed for pure fluid (air). I am unable to solve this issue. It will be a big help for me if someone can help me in solving this issue. Thank You.
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Aarthy, PG Student, National Institute of Technology, Trichy, India. 

December 30, 2016, 06:28 

#2 
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Join Date: Sep 2011
Posts: 39
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I am also struggling with the same problem. How can one determine the number of particles injected and mass flow rate. In my case I am using a surface injection from the inlet.


July 7, 2017, 16:03 

#3 
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Join Date: Jan 2017
Posts: 25
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Dear frends,
The number of particle you can plot in particlr varialbe particle number in parcels, graph particle trackparticle varaibleparticle number in parcel further you can also calculate it I have the same problem with the plot reading about DPM property. can you guys share your solution. thanks 

October 25, 2019, 21:49 

#4 
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Steve Ying
Join Date: Apr 2019
Posts: 2
Rep Power: 0 
I am also struggling with the same problem. I got the results too, there is no change in mean Nusselt number. It is same as that observed for pure fluid.


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dpm in fluent, fluent 14.5, nanofluid modelling 
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