Extracting the intermediate solution variables in simscape

I am using hydraulic resistive tube in my piping network. Which tube element incorporates elevation difference between its ends (like if its inclined or vertical pipes). I want to account this using aggregate equivalent length option in resistive tube element. Is it possible? If so how can I?

If I know the friction factor which it calculates during the solution process (available in source code), I can use it in other mathematial operation blocks. But cnt find how to check this value it calculates during the solution process.

Can anyone share how to do this??

Answer 1

[Yifeng Tang]

Two quick ways I can think of:

1. Add a variable. In equations, add "new_var == intermediate_var;".
2. Move code out of "let ... in ..." and use the "intermediate" syntax. Below is an example from the pipe block in the isothermal liquid domain:

intermediates (Access = private, ExternalAccess = none)
    p_A = A.p; % Pressure at port A
    p_B = B.p; % Pressure at port B
end

% For logging
intermediates (Access = private)
    rho_I = foundation.isothermal_liquid.mixture_density(p_I, ...
        A.bulk_modulus_model, A.air_dissolution_model, A.rho_L_atm, A.beta_L_atm, A.beta_gain, ...
        A.air_fraction, A.rho_g_atm, A.polytropic_index, A.p_atm, A.p_crit, A.p_min); % Density of liquid volume
end
    

The variables in the second section of the "intermediates" should show up in the simlog and Simscape Results Explorer. More help on this syntax here:

https://www.mathworks.com/help/releases/R2022a/physmod/simscape/lang/intermediates.html

And speaking of the isothermal liquid (IL) domain, use IL instead of the hydraulic domain whenever you can

https://www.mathworks.com/help/physmod/simscape/ug/upgrading-hydraulic-models-to-use-isothermal-liquid-blocks.html