[RonSwanson]

I have been trying to optimise a nozzle for maximum mass flow/discharge coeff. The flow solver and adjoint converge well. However The FFD box creates very jagged intersections with non deforming part of the wall.

I have tried to modify my FFD box in numerous ways through position and size, as well as the numerous .cfg controls for optimisation. I have attached some pictures.

This has also occurred when using Hicks-Henne.

Does anybody have any suggestions?

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I have also found a minor bug when optimising for mass flow:
-Adjoint solver creates adjres_mfr.dat
-Optimiser calls adjres_mfw.dat, causing it to fail
-The bug is located in bin/SU2/io/tools.py -- line 431

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Regards,
Ross.

[RonSwanson]

My supervisor suggested a fix, which works perfectly. If you create an extra 2 FFD sections either side of the, deformable area and set them to 0 degrees of freedom then you lock the geometry of these sections and the curvature throughout is smoothed.

Cheers,
Ross.

Edit (13/05/15): Sorry all a further issue I have come across is the way the solver treats the objective mass flow function. My nozzle was attempting to shrink itself and thus choke, reducing mass flow. In my case I want to maximize mass flow, I'm not sure if it's a bug but again in tools.py line 360 the following is present

# -------------------------------------------------------------------
# Get Objective Function Sign
# -------------------------------------------------------------------

def get_objectiveSign( ObjFun_name ):
""" returns -1 for maximization problems:
LIFT
EFFICIENCY
THRUST
FIGURE_OF_MERIT
returns +1 otherwise
"""

# flip sign for maximization problems
if ObjFun_name == "LIFT" : return -1.0
if ObjFun_name == "EFFICIENCY" : return -1.0
if ObjFun_name == "THRUST" : return -1.0
if ObjFun_name == "FIGURE_OF_MERIT" : return -1.0

# otherwise
return 1.0

#: def get_objectiveSign()

I have edited it to and this could be perfromed with any other obj. func.

# -------------------------------------------------------------------
# Get Objective Function Sign
# -------------------------------------------------------------------

def get_objectiveSign( ObjFun_name ):
""" returns -1 for maximization problems:
LIFT
EFFICIENCY
THRUST
FIGURE_OF_MERIT
returns +1 otherwise
"""

# flip sign for maximization problems
if ObjFun_name == "LIFT" : return -1.0
if ObjFun_name == "EFFICIENCY" : return -1.0
if ObjFun_name == "THRUST" : return -1.0
if ObjFun_name == "FIGURE_OF_MERIT" : return -1.0
if ObjFun_name == "MASS_FLOW_RATE" : return -1.0

# otherwise
return 1.0

#: def get_objectiveSign()