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 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 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
-# Post-pro
-cfg['Slice'] = list of float # y-coordinates of cutting planes to extract slices on the geometry (optional, will only work with VTK)
-cfg['TagId'] = int # id of physical group to be sliced (id can be obtained through gmsh)
-```
-Additional parameters specific to Polar class:
-```python
-cfg['AoA_begin'] = float # first value of the angle of attack [degrees]
-cfg['AoA_end'] = float # last value of the angle of attack [degrees]
-cfg['AoA_step'] = float # step in the angle of attack [degrees]
-```
-Additional parameters specific to Trim class:
-```python
-cfg['CL'] = float # target lift coefficient
-cfg['AoA'] = float # guess (first) angle of attack
-cfg['dCL'] = float # guess (first) slope of CL w.r.t AoA [1/rad]
-```
-
-**2. Using the solver**  
-After the parameters have been defined, the solver can be set up automatically by instantiating the object as,
-```python
-import dart.api.internal.polar as pol
-polar = pol.Polar(cfg)
-# or
-import dart.api.internal.trim as trm
-trim = trm.Trim(cfg)
-```
-The script can then be run by calling,
-```python
-polar.run()
-# or
-trim.run()
-```
-Finally, the results can be displayed using,
-```python
-polar.disp()
-# or
-trim.disp()
-```
+## 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 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 internal APIs use the [Core API](use_api_core) to initialize DART using a dictionary of parameters. Additional configuration dicts must be provided and are listed hereunder.  
+Additional dict for post-processing:
+```python
+post_cfg = {
+    'cut_tag': int # id of physical group to be sliced (can be obtained through Gmsh)
+    'y_slices': list(float) # y-coordinates of cutting planes to extract slices on the geometry (will only work if output format is VTK)
+}
+```
+Additional dict for polar calculation:
+```python
+polar_cfg = {
+    'aoas': list(float) # list of angles of attack [deg] (optional, default=[0])
+}
+```
+Additional dict for trim calculation:
+```python
+trim_cfg = {
+    'cl_target': float, # target lift coefficient (optional, default=0)
+    'aoa_init': float, # guess (first) angle of attack [deg] (optional, default=0)
+    'cl_slope': float # guess (first) slope of CL w.r.t AoA [1/rad] (optional, default=6.3)
+}
+```
+
+**2. Using the solver**  
+After the parameters have been defined, the solver can be set up automatically by instantiating the object as,
+```python
+import dart.api.internal.polar as pol
+polar = pol.Polar(cfg, polar_cfg, post_cfg=None)
+# or
+import dart.api.internal.trim as trm
+trim = trm.Trim(cfg, trim_cfg, post_cfg=None)
+```
+The script can then be run by calling,
+```python
+polar.run()
+# or
+trim.run()
+```
+Finally, the results can be displayed using,
+```python
+polar.disp()
+# or
+trim.disp()
+```