/EOS/IDEAL-GAS-VT
Block Format Keyword Describes the equation of state for ideal gas (volume - temperature).
Describes the equation of state for ideal gas P=ρrT ; where, cp is temperature dependent and described with Janaf model: cp(T)=A0+A1T+A2T2+A3T3+A4T4 (SI: J.kg−1.K−1 )
Format
(1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) | (10) |
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/EOS/IDEAL-GAS-VT/mat_ID/unit_ID | |||||||||
eos_title | |||||||||
r | T0 | P0 | Psh | ||||||
A0 | A1 | A2 | A3 | A4 |
Definition
Field | Contents | SI Unit Example |
---|---|---|
mat_ID | Material identifier. (Integer, maximum 10 digits) |
|
unit_ID | Unit identifier. (Integer, maximum 10 digits) |
|
eos_title | EOS title. (Character, maximum 100 characters) |
|
r | Ideal gas
constant. (Real) |
[J.kg−1.K−1] |
T0 | Initial temperature. If
P0 not defined, refer to Comment 3. (Real) |
[K] |
P0 | Initial pressure. If T0 is not defined, refer to Comment 3. (Real) |
[Pa] |
Psh | Pressure
shift. (Real) |
[Pa] |
A0 | Specific heat capacity
parameter. (Real) |
[Jkg.K] |
A1 | Specific heat capacity
parameter. (Real) |
[Jkg.K2] |
A2 | Specific heat capacity
parameter. (Real) |
[Jkg.K3] |
A3 | Specific heat capacity
parameter. (Real) |
[Jkg.K4] |
A4 | Specific heat capacity
parameter. (Real) |
[Jkg.K5] |
▸Example (Air)
Comments
- Ideal gas EOS is
PV=RT
Where,
- V
- Volume
- R
- Universal ideal gas constant (SI: J.kg−1mol−1 )
- T
- Temperature
It can also be written Pv=rT or P=ρrT .
Where,- v
- Specific volume ( v=1/ρ )
- r
- Gas constant (SI: J.kg−1K−1 ), r=R/M ; where, M is molecular mass
- Alternative form of
ideal gas is /EOS/IDEAL-GAS-VE (Volume
Energy):P(μ,E)=(γ−1)(1+μ)EWhere,
- γ=cpcv
- Is constant
- µ=ρρ0−1
- E=EintV0
Consequently, when γ is constant, defining A0=cp=γrγ−1 , and A1=A2=A3=A4=0 will provide the same equation of state as /EOS/IDEAL-GAS-VE formulation.
- If T0 is defined, then P0 is
computed:P0=r.ρ0.T0
Otherwise, if P0 is defined, then T0 is computed:
T0=P0/r.ρ0 - The
cp(T)
function is provided with Janaf
model:cp(T)=A0+A1T+A2T2+A3T3+A4T4
(SI: J.kg−1.K−1 )
- Equations of state are used by Radioss to compute the hydrodynamic pressure and are compatible with the material laws: