CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > ANSYS > CFX

Porous domain:Interfacial area density and heat transfer coefficient

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   September 7, 2012, 06:22
Default Porous domain:Interfacial area density and heat transfer coefficient
  #1
New Member
 
Join Date: Sep 2012
Location: Europe
Posts: 25
Rep Power: 13
l.te is on a distinguished road
Hello, I'm building a model for a cure of a composite material with CFX. The exact process that I'm simulating is a pultrusion. I have an heated steel die with a fiberglass-epoxy resin composite that proceed at a low speed in the die to be heated. I have modeled the composite material with a "Porous domain" where there is a fluid (epoxy-resin) and a solid (fiberglass). When I define the porous domain, under the "Porosity settings tab" the model ask for the "Interfacial area density" and the "heat transfer coefficient" between the fluid and solid parts. I have read the cfx pre user's guide, solver theory guide and solver modeling guide founding a few information about how to assign these values.
These are my 2 questions:
1)For the interfacial area density, I have read that it is the area of contact between the two phases in the porous domain for an unit volume (A/V). If I have the volume fiber fraction of my composite (Vf=0.639) and the composite diameter (it is a rod, D=0.0025 m) and the circumference of a single continous fiber (8.17*10^-5 m), can I calculate the "Interfacial area density" value specifying the area of contact between the resin and the total number of fibre contained in a unit volume of composite (I obtain a value about 98000m^2/m^3)?
2) Fiberglass and epoxy resin that I have as phases in my composite are both continue and for the heat transfer coefficient to specify in "Porosity settings tab" the guide refers to an inhomogeneous interphase heat transfer models in the "Solver theory guide". Reading this section I can find three models: "Particle model correlations" (for one continue phase and one dispersed phase, not my case), "Mixture models correlations" (for two continue phases, this is my case)and the "Two resistance model". Reading the "Mixture models correlations", the Solver theory guide refers to the "Mixture model correlations for Overall Heat Transfer Coefficient" in Solver Modeling Guide and here, to finally calculate the heat tranfer coefficient, refer to the previous paragraph "Particle Model Correlations for overall heat transfer coefficient ": the problem is that here to calculate the heat transfer, it refers to a dispersed particle that moves in a fluid (So it calculates "h" through Nusselt, Reynolds and Prandtl, that have a sense with a fluid, but not with a solid phase)! How I can do to calculate this heat tranfer coefficient?

Thank for the patience
l.te is offline   Reply With Quote

Old   September 9, 2012, 12:34
Unhappy
  #2
New Member
 
Join Date: Sep 2012
Location: Europe
Posts: 25
Rep Power: 13
l.te is on a distinguished road
Quote:
Originally Posted by l.te View Post
Hello, I'm building a model for a cure of a composite material with CFX. The exact process that I'm simulating is a pultrusion. I have an heated steel die with a fiberglass-epoxy resin composite that proceed at a low speed in the die to be heated. I have modeled the composite material with a "Porous domain" where there is a fluid (epoxy-resin) and a solid (fiberglass). When I define the porous domain, under the "Porosity settings tab" the model ask for the "Interfacial area density" and the "heat transfer coefficient" between the fluid and solid parts. I have read the cfx pre user's guide, solver theory guide and solver modeling guide founding a few information about how to assign these values.
These are my 2 questions:
1)For the interfacial area density, I have read that it is the area of contact between the two phases in the porous domain for an unit volume (A/V). If I have the volume fiber fraction of my composite (Vf=0.639) and the composite diameter (it is a rod, D=0.0025 m) and the circumference of a single continous fiber (8.17*10^-5 m), can I calculate the "Interfacial area density" value specifying the area of contact between the resin and the total number of fibre contained in a unit volume of composite (I obtain a value about 98000m^2/m^3)?
2) Fiberglass and epoxy resin that I have as phases in my composite are both continue and for the heat transfer coefficient to specify in "Porosity settings tab" the guide refers to an inhomogeneous interphase heat transfer models in the "Solver theory guide". Reading this section I can find three models: "Particle model correlations" (for one continue phase and one dispersed phase, not my case), "Mixture models correlations" (for two continue phases, this is my case)and the "Two resistance model". Reading the "Mixture models correlations", the Solver theory guide refers to the "Mixture model correlations for Overall Heat Transfer Coefficient" in Solver Modeling Guide and here, to finally calculate the heat tranfer coefficient, refer to the previous paragraph "Particle Model Correlations for overall heat transfer coefficient ": the problem is that here to calculate the heat transfer, it refers to a dispersed particle that moves in a fluid (So it calculates "h" through Nusselt, Reynolds and Prandtl, that have a sense with a fluid, but not with a solid phase)! How I can do to calculate this heat tranfer coefficient?

Thank for the patience
Hello, can anyone help me, please?
l.te is offline   Reply With Quote

Old   May 18, 2014, 00:45
Default
  #3
New Member
 
EvanOscarSmith's Avatar
 
Evan Oscar Smith
Join Date: Jan 2012
Location: Canberra, Australia
Posts: 6
Rep Power: 14
EvanOscarSmith is on a distinguished road
Hey I.te,

Did you ever solve this problem?
EvanOscarSmith is offline   Reply With Quote

Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
mass flow in is not equal to mass flow out saii CFX 12 March 19, 2018 06:21
Simulation of a single bubble with a VOF-method Suzzn CFX 21 January 29, 2018 01:58
Water subcooled boiling Attesz CFX 7 January 5, 2013 04:32
Constant velocity of the material Sas CFX 15 July 13, 2010 09:56
Two-Phase Buoyant Flow Issue Miguel Baritto CFX 4 August 31, 2006 13:02


All times are GMT -4. The time now is 01:32.