A How can I calculate the R value for a solid in OpenFOAM CFD modeling?

AI Thread Summary
In CFD modeling of gas-solid flow using OpenFOAM, the solid's flow is modeled as a perfect fluid, with density calculated using the equation ρ = P/RT + ρo. The challenge lies in determining the value of R for solids, as existing OpenFOAM documentation primarily provides values for fluids like water and mercury. Attempts to derive R through plotting density against pressure and temperature have been inconclusive, and there is a lack of resources on this topic. The user suggests that finding a database for specific solids' densities could help approximate R. Overall, there is a need for clearer guidance on applying the ideal gas law to solids in OpenFOAM.
rasikaj
Messages
2
Reaction score
0
During CFD modeling of a gas-solid flow, flow of solid was modeled as a perfect fluid using OpenFOAM.

The density of the perfect fluid is calculated using the following equation as given in the documentation.

ρ = P/RT + ρo , where ρo is the density at T = 0 kelvin, ρ is the density of the perfect fluid at pressure P (Pa) and temperature T (K). There is no other mention about this in the documentation of OpenFOAM.

My struggle is to calculate the R (J kg -1 K-1) for the solid. In the OpenFOAM tutorials for the normal conditions of water R = 3000 with ρo = 1027 kg m-3.

Also for mercury
R = 6818 with ρo = 13529 kg m-3.

I tried to plot the ρ with P/T for water and the linear equation was

ρ = 0.4321 (P/T) + 848.78, where R = 2.314

So could anyone please tell me how to calculate R for a certain fluid or solid. I have searched the internet for days and still didn't find any reference to this equation.
 
Physics news on Phys.org
I'm still tryng to figure out how you are applying the ideal gas law to solids and liquids.
 
  • Like
Likes rasikaj
Actually this is the equation, OpenFOAM has mentioned in their user guide. Not my idea. I thought this is some physics that I cannot understand.

You can see the equation in page U-203 of their user guide. Here is the link.
http://foam.sourceforge.net/docs/Guides-a4/OpenFOAMUserGuide-A4.pdf

I have seen the same problem asked in cfd-online.com, but with no answers

https://www.cfd-online.com/Forums/o...velopment/195068-r-constant-perfet-fluid.html

Thanks for your comment anyway. I would be grateful if you could give me a solution.
 
I have no idea too, but the only thing that you can do -i think- is to look in some database for ##\rho_0## and ##\rho## for the solid you are interested in and then calculate an approximation of R.
 
Thread 'Gauss' law seems to imply instantaneous electric field propagation'

Thread 'Gauss' law seems to imply instantaneous electric field propagation'

Imagine a charged sphere at the origin connected through an open switch to a vertical grounded wire. We wish to find an expression for the horizontal component of the electric field at a distance ##\mathbf{r}## from the sphere as it discharges. By using the Lorenz gauge condition: $$\nabla \cdot \mathbf{A} + \frac{1}{c^2}\frac{\partial \phi}{\partial t}=0\tag{1}$$ we find the following retarded solutions to the Maxwell equations If we assume that...
View full post »

Thread 'Do electron density waves accompany EM waves in coaxial cables?'

Maxwell’s equations imply the following wave equation for the electric field $$\nabla^2\mathbf{E}-\frac{1}{c^2}\frac{\partial^2\mathbf{E}}{\partial t^2} = \frac{1}{\varepsilon_0}\nabla\rho+\mu_0\frac{\partial\mathbf J}{\partial t}.\tag{1}$$ I wonder if eqn.##(1)## can be split into the following transverse part $$\nabla^2\mathbf{E}_T-\frac{1}{c^2}\frac{\partial^2\mathbf{E}_T}{\partial t^2} = \mu_0\frac{\partial\mathbf{J}_T}{\partial t}\tag{2}$$ and longitudinal part...
View full post »
Thread 'Recovering Hamilton's Equations from Poisson brackets'

Thread 'Recovering Hamilton's Equations from Poisson brackets'

The issue : Let me start by copying and pasting the relevant passage from the text, thanks to modern day methods of computing. The trouble is, in equation (4.79), it completely ignores the partial derivative of ##q_i## with respect to time, i.e. it puts ##\partial q_i/\partial t=0##. But ##q_i## is a dynamical variable of ##t##, or ##q_i(t)##. In the derivation of Hamilton's equations from the Hamiltonian, viz. ##H = p_i \dot q_i-L##, nowhere did we assume that ##\partial q_i/\partial...
View full post »

Similar threads

I Static sphere with gravitating fluid
Replies
6
Views
1K
B How can I model a density function of a compressible fluid?
Replies
2
Views
2K
I Atmospheric Density vs Altitude in an O'Neil Cylinder
Replies
1
Views
3K
I Fragmentation of a drop in a miscible fluid
Replies
2
Views
1K
Modeling Air Compression Cylinder
Replies
45
Views
5K
I How to understand experiment to measure heat capacity of solid?
Replies
1
Views
2K
Calculations using the Standard Solar Model & Solar Equations of State
Replies
1
Views
2K
How can I calculate the Reynolds number if the particle velocity is unknown?
Replies
14
Views
6K
Not sure Exactly what Pressure I am Solving for in this Form
Replies
13
Views
2K
I Energy Density in SR Energy-Momentum Tensor
Replies
12
Views
2K

Hot Threads

Recent Insights

Back
Top