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-   -   eilmer3: equilibrium air look-up table (https://www.cfd-online.com/Forums/main/177575-eilmer3-equilibrium-air-look-up-table.html)

l.loiodice September 16, 2016 10:33

eilmer3: equilibrium air look-up table
 
Hi everybody,
i'm working on Eilmer3 software. I don't understand the meaning of the look-up table about the air in chemical equilibrium, this is a part of the array:


-- Auto-generated by build-cea-lut on: 17-Jan-2011 07:52:02
model = 'look-up table'
iesteps = 400
irsteps = 50
emin = 143084
de = 142861
lrmin = -6
dlr = 0.16
data = {
{
{715.346, 715.35, 287.05, 1.40125, 1.36261e-05, 0.0188266},
{715.346, 715.341, 287.059, 1.4012, 1.36261e-05, 0.0188266},
{715.346, 715.342, 287.058, 1.40121, 1.36261e-05, 0.0188266},
{715.346, 715.347, 287.053, 1.40123, 1.36261e-05, 0.0188266},
{715.346, 715.346, 287.054, 1.40122, 1.36261e-05, 0.0188266},
etc..
What does these values refer to?

nepomaof September 18, 2016 08:15

Eilmer 3: equilibrium air look up table
 
Hi there,

Are you referring to eilmer3 code from UQ?

These numbers I guess like the following:

{Temperature, ?, Universal Gas Constant R, (Cp/Cv) Gamma, Viscosity, Density}

Not sure about the 2nd term - looks like the first term, with slight changes..

Cheers!
Sree.

l.loiodice September 19, 2016 03:55

Thank you Sree,

yes, eilmer3 code from UQ,

I found the source code of the look-up table:
#ifndef LOOK_UP_TABLE_HH
13 #define LOOK_UP_TABLE_HH
14
15 #include <string>
16
17 #include "gas_data.hh"
18 #include "gas-model.hh"
19
20 class Look_up_table : public Gas_model {
21 public:
22 Look_up_table(const std::string cfile);
23 ~Look_up_table();
24 private:
25 int determine_interpolants(const Gas_data &Q, int &ir, int &ie,
26 double &lrfrac, double &efrac);
27 int s_eval_thermo_state_rhoe(Gas_data &Q);
28 int s_eval_transport_coefficients(Gas_data &Q);
29 int s_eval_diffusion_coefficients(Gas_data &Q);
30 double s_molecular_weight(int isp);
31 double s_internal_energy(const Gas_data &Q, int isp);
32 double s_enthalpy(const Gas_data &Q, int isp);
33 double s_entropy(const Gas_data &Q, int isp);
34 double s_dedT_const_v(const Gas_data &Q, int &status);
35 double s_dhdT_const_p(const Gas_data &Q, int &status);
36 double s_gas_constant(const Gas_data &Q, int &status);
37
38 bool with_entropy;
39 double s1_, p1_, T1_;
40 int iesteps_, irsteps_;
41 double emin_, emax_, de_;
42 double lrmin_, lrmax_, dlr_;
43
44 matrix Cv_hat_;
45 matrix Cv_;
46 matrix R_hat_;
47 matrix g_hat_;
48 matrix mu_hat_;
49 matrix k_hat_;
50 matrix Cp_hat_;
51 };
52
53 Gas_model* create_look_up_table_gas_model(const std::string cfile);
54
55 #endif

But I still don't understand the meaning of the first two values of the array and what "_hat_" refers to in the source code

Cheers,
Luigi


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