use_api_internal.md

 ## Internal API
 The internal API is meant for users wanting to run a standard computational procedure on a classic lifting configuration. The procedures that are currently implemented can be found under [api/internal](https://gitlab.uliege.be/am-dept/dartflo/blob/master/dart/api/internal):
 - a [polar](https://gitlab.uliege.be/am-dept/dartflo/blob/master/dart/api/internal/polar.py) analysis, to compute the aerodynamic coefficients for various angles of attack,
-- a [trim](https://gitlab.uliege.be/am-dept/dartflo/blob/master/dart/api/internal/trim.py) analysis, to find the angle of attack to produce a desired lift coefficient.
+- a [trim](https://gitlab.uliege.be/am-dept/dartflo/blob/master/dart/api/internal/trim.py) analysis, to find the angle of attack that produces a desired lift coefficient.
 Sample cases making use of the internal API can be found under [cases](https://gitlab.uliege.be/am-dept/dartflo/blob/master/dart/cases).
 
 **1. Defining the parameters**  
-In practise, all the classes implementing a computational procedure inherit from Config, which setups the solver. The first step thus consists in instantiating the desired class and passing it the parameters as a python dictionary. The different parameters are listed hereunder.  
-Common parameters (used in Config class):
+In practise, all the internal APIs use the [Core API](use_api_core) to initialize DART using a dictionary of parameters. Some additional parameters need to be defined and are listed hereunder.  
+Additional common parameters:
 ```python
-p = {}
-# I/O
-p['Dim'] = int # dimension of the problem (2 or 3)
-p['Format'] = str # output format ('gmsh' or 'vtk')
-p['File'] = str # path to the geometry/mesh file
-p['Pars'] = dict # keys/values of parameters or options to be passed to gmsh (can be empty)
-# Groups...
-p['Fluid'] = str # bame of mesh group containing the fluid
-p['Farfield'] = list of str # names of mesh groups containing the farfield boundaries (downstream boundary should be last element)
-# ... only for 2D
-p['Wing'] = str # name of mesh group containing the airfoil boundary
-p['Wake'] = str # name of mesh group containing the wake
-p['Te'] = str # name of mesh group containing the trailing edge
-# ... only for 3D
-p['Wings'] = list of str # names of mesh groups containing the lifting surface boundary
-p['Wakes'] = list of str # names of mesh groups containing the wake
-p['WakeTips'] = list of str # names of mesh groups containing the edge of the wakes
-p['TeTips'] = list of str # names of mesh groups containing the edge of the wakes and the trailing edges
-# Freestream and reference values
-p['M_inf'] = float # freestream Mach number
-p['S_ref'] = float # reference surface length (= c_ref for 2D)
-p['c_ref'] = float # reference chord length
-p['x_ref'] = float # x-coordinate of reference point for moment computation
-p['y_ref'] = float # y-coordinate of reference point for moment computation
-p['z_ref'] = float # z-coordinate of reference point for moment computation
-# Linear solver...
-p['LSolver'] = str # linear solver type (Pardiso, GMRES, MUMPS or SparseLU)
-# ... only for GMRES
-p['G_fill'] = int # fill-in factor for GMRES ILU preconditioner
-p['G_tol'] = float # tolerance for GMRES solver
-p['G_restart'] = int # number of restart for GMRES solver
-# Nonlinear solver...
-p['NSolver'] = str # nonlinear solver type (Picard or Newton)
-p['Rel_tol'] = float # relative tolerance on solver residual
-p['Abs_tol'] = float # absolute tolerance on solver residual
-p['Max_it'] = int # solver maximum number of iterations
-# ... only for Picard
-p['Relaxation'] = float # relaxation parameter (preffered value: 0.7)
-# ... only for Newton
-p['LS_tol'] = float # tolerance on line search residual (preffered value: 1e-6)
-p['Max_it_LS'] = int # line search maximum number of iterations (preffered value: 10)
-p['AV_thrsh'] = float # residual threshold below which the artificial viscosity is decreased (preffered value: 1e-2)
-# Various optional parameters
-p['Slice'] = list of float # y-coordinates of cutting planes to extract slices on the geometry
+# Post-pro
+p['Slice'] = list of float # y-coordinates of cutting planes to extract slices on the geometry (optional, will only work with VTK)
 p['TagId'] = int # id of physical group to be sliced (id can be obtained through gmsh)
-p['Symmetry'] = str # name of the mesh group containing the symmetry boundary
-p['AoS'] = float # angle of sideslip [degrees]
 ```
 Additional parameters specific to Polar class:
 ```python