Post-processing

Post-processing#

This chapter is an introduction or a reminder on the types of post-processing available in TrioCFD/TRUST (section 1.1) as well as the various variables accessible (section 1.2) for correctly visualizing the TrioCFD multiphase calculations.

Types of post-processing#

Regarding the case under study and the variables of interest, TRUST offers a range of options for post-processing:

Individual points of interest (’Point’ keyword),
Distributed points along a linear path ( ‘Segment’ keyword),
Points arranged according to a predefined layout (’Plan’ keyword),
Points arranged within a parallelepiped structure (’Volume’ keyword),
Fields across the entire domain. The ‘Fields’ keyword demands specifying the field’s location on the mesh (faces, elements, or vertices), the field’s name, the post-processing time, and a backup file,
Statistical measurement can be applied to fields to compute the mean value, standard deviation, or correlation between two fields.The ‘Statistics’ keyword requires defining a time window, time step, and the desired statistical methods.

Variables easily accessible#

In order to ease computation post-processing, some variables are already accessible with keywords. They are summarized in the following tables.

Mesh-related keyword#

Name	Notation	Keyword	Unit
Cell volumes	\(V_{cell}\)	`Volume_maille`	\(m^3\)
Stability time steps	\(\Delta t\)	`Pas_de_temps`	\(s\)
Volumetric porosity	\(\epsilon\)	`Porosite_volumique`
Distance to the wall	\(y_w\)	`Distance_Paroi`	\(m\)
Cell Courant number (VDF only)	\(C_o=\frac{u\Delta t}{\Delta x}\)	`Courant_maille`
Cell Reynolds number (VDF only)	\(Re=\frac{u\Delta x}{\nu}\)	`Reynolds_maille`

Mass keywords#

Name	Notation	Keyword	Unit
Density	\(\rho\)	`masse_volumique`	\(kg.m^{-3}\)
Void fraction	\(\alpha\)	`Alpha`	dimensionless
Mass balance on each cell	\(\nabla \cdot u\)	`Divergence_U`	\(m^3.s^{-1}\)

Momentum equation keywords#

Name	Notation	Keyword	Unit
Velocity	\(u\)	`Vitesse` or `Velocity`	\(m.s^{-1}\)
Velocity residual	\(u_{res}\)	`Vitesse_residu`	\(m.s^{-2}\)
Kinetic energy per elements	\(\frac{1}{2}\rho u^2\)	`Energie_cinetique_elem`	\(kg.m^{-1}.s^{-2}\)
Total kinetic energy	\(\frac{1}{2}\rho u^2\)	`Energie_cinetique_totale`	\(kg.m^{-1}.s^{-2}\)
Vorticity	\(w=rotu\)	`Vorticite`	\(s^{-1}\)
Pressure in incompressible flow	\(\frac{P}{\rho}+ gz\)	`Pression`	\(Pa.m^3.kg^{-1}\)
Pressure in incompressible flow	\(P+\rho\) gz	`Pression_pa` or `Pressure`	\(Pa\)
Pressure in compressible flow	\(P\)	`Pression`	\(Pa\)
Hydrostatic pressure	\(\rho gz\)	`Pression_hydrostatique`	\(Pa\)
Total pressure	\(P_{tot}\)	`Pression_tot`	\(Pa\)
Pressure gradient	\(\nabla (\frac{P}{\rho}+ gz)\)	`Gradient_pression`	\(m.s^{-2}\)
Velocity gradient	\(\nabla u\)	`gradient_vitesse`	\(s^{-1}\)
Local shear strain rate	\(\sqrt{2S_{ij}S_{Sij}}\)	`Taux_cisaillement`	\(s^{-1}\)
Viscous force		`Viscous_force`	\(kg.m^2.s^{-1}\)
Pressure force		`Pressure_force`	\(kg.m^2.s^{-1}\)
Total force		`Total_force`	\(kg.m^2.s^{-1}\)
Viscous force along X		`Viscous_force_x`	\(kg.m^2.s^{-1}\)
Viscous force along Y		`Viscous_force_y`	\(kg.m^2.s^{-1}\)
Viscous force along Z		`Viscous_force_z`	\(kg.m^2.s^{-1}\)
Pressure force along X		`Pressure_force_x`	\(kg.m^2.s^{-1}\)
Pressure force along Y		`Pressure_force_y`	\(kg.m^2.s^{-1}\)
Pressure force along Z		`Pressure_force_z`	\(kg.m^2.s^{-1}\)
Total force along X		`Total_force_x`	\(kg.m^2.s^{-1}\)
Total force along Y		`Total_force_y`	\(kg.m^2.s^{-1}\)
Total force along Z		`Total_force_z`	\(kg.m^2.s^{-1}\)
Component velocity along X	\(u_X\)	`VitesseX`	\(m.s^{-1}\)
Component velocity along Y	\(u_Y\)	`VitesseY`	\(m.s^{-1}\)
Component velocity along Z	\(u_Z\)	`VitesseZ`	\(m.s^{-1}\)
Source term in non Galinean referential	\(a\)	`Acceleration_terme_source`	\(m.s^{-2}\)

Energy equation keywords#

Name	Notation	Keyword	Unit
Temperature	\(T\)	`Temperature`	\(K\)
Temperature residual	\(T_{res}\)	`Temperature_residu`	\(K.s^{-1}\)
Temperature variance	\(Var(T)\)	`Variance_Temperature`	\(K^{2}\)
Temperature dissipation rate		`Taux_Dissipation_Temperature`	\(K^2.s^{-1}\)
Temperature gradient	\(\nabla T\)	`Gradient_temperature`	\(K.m^{-1}\)
Heat exchange coefficient	\(h\)	`H_echange_Tref`	\(W.m^{-2}.K^{-1}\)
Internal energy	\(U\)	`energie_interne`	\(J\)
Enthalpy	\(H\)	`enthalpie`	\(J\)
Irradiancy	\(I\)	`Irradiance`	\(W.m^{-2}\)
Volumic thermal power	\(P_w\)	`Puissance_volumique`	\(W.m^{-3}\)

Turbulence equations keywords#

Name	Notation	Keyword	Unit
Turbulent viscosity	\(\nu_t\)	`Viscosite_turbulente`	\(m^2.s^{-1}\)
Turbulent dynamic viscosity	\(\mu_t\)	`Viscosite_dynamique_turbulente`	\(kg.m.s^{-1}\)
Turbulent kinetic energy	\(\rho k\)	`Energy`	\(kg.m^2.s^{-2}\)
Turbulent dissipation rate	\(\varepsilon\)	`Eps`	\(m^2.s^{-3}\)
Specific dissipation rate	\(\omega\)	`omega`	\(s^{-1}\)
Specific dissipation time scale	\(\tau\)	`tau`	\(s\)
Q-criteria	\(Q\)	`Critere_Q`	\(s^{-1}\)
Distance to the wall	\(y^+\)	`Y_plus`
Friction velocity	\(u^*\)	`U_star`	\(m.s^{-1}\)
Turbulent heat flux		`Flux_Chaleur_Turbulente`	\(m.K.s^{-1}\)

Two-phase models keywords#

Name	Notation	Keyword	Unit
Drag force	\(F_D\)	`Drag`	\(N.m^{-3}\)
Lift force	\(F_L\)	`Lift`	\(N.m^{-3}\)
Dispersion force	\(F_{Disp}\)	`Disp`	\(N.m^{-3}\)
Lubrication force	\(F_{Lub}\)	`Lub`	\(N.m^{-3}\)
Bubble diameter	\(d_b\)	`d_bulles`	\(m\)

Let’s notice that physical properties (conductivity, diffusivity, etc) can also be post-processed. Furthermore, the Definitionchamps keyword can be used to create new or more complex fields for advanced post-processing.