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Package esys :: Package escript :: Module levelset :: Class LevelSet
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Class LevelSet

The level set method tracking an interface defined by the zero contour of the level set function phi which defines the signed distance of a point x from the interface. The contour phi(x)=0 defines the interface.

It is assumed that phi(x)<0 defines the volume of interest, phi(x)>0 the outside world.

Instance Methods [hide private]
 
__advect(self, dt)
Advects the level set function in the presence of a velocity field.
 
__init__(self, phi, reinit_max=10, reinitialize_after=20, smooth=2.0, useReducedOrder=False)
Sets up the level set method.
 
__makeInterface(self, phi, smoothing_width)
Creates a smooth interface from -1 to 1 over the length 2*h*smoothing_width where -1 is used where the level set is negative and 1 where the level set is 1.
 
__reinitialise(self)
Reinitializes the level set.
 
getAdvectionSolverOptions(self)
Returns the solver options for the interface advective.
 
getDomain(self)
Returns the domain.
 
getH(self)
Returns the mesh size.
 
getLevelSetFunction(self)
Returns the level set function.
 
getReinitializationSolverOptions(self)
Returns the options of the solver for the reinitialization
 
getTimeStepSize(self, velocity)
Returns a new dt for a given velocity using the Courant condition.
 
getVolume(self)
Returns the volume of the phi(x)<0 region.
 
makeCharacteristicFunction(self, contour=0, phi=None, positiveSide=True, smoothing_width=None)
Makes a smooth characteristic function of the region phi(x)>contour if positiveSide and phi(x)<contour otherwise.
 
update(self, dt)
Sets a new velocity and updates the level set function.
 
update_parameter(self, param_neg=-1, param_pos=1, phi=None, smoothing_width=None)
Creates a smoothed function with param_neg where phi<0 and param_pos where phi>0 which is smoothed over a length smoothing_width across the interface.
 
update_parameter_sharp(self, param_neg=-1, param_pos=1, phi=None)
Creates a function with param_neg where phi<0 and param_pos where phi>0 (no smoothing).
 
update_phi(self, velocity, dt)
Updates phi under the presence of a velocity field.
Method Details [hide private]

__advect(self, dt)

 
Advects the level set function in the presence of a velocity field.
Parameters:
  • dt - time increment
Returns:
the advected level set function

__init__(self, phi, reinit_max=10, reinitialize_after=20, smooth=2.0, useReducedOrder=False)
(Constructor)

 
Sets up the level set method.
Parameters:
  • phi - the initial level set function
  • reinit_max - maximum number of reinitialization steps
  • reinitialize_after - phi is reinitialized every reinit_after step
  • smooth - smoothing width

__reinitialise(self)

 

Reinitializes the level set.

It solves the PDE...

Returns:
reinitialized level set

getTimeStepSize(self, velocity)

 
Returns a new dt for a given velocity using the Courant condition.
Parameters:
  • velocity - velocity field

makeCharacteristicFunction(self, contour=0, phi=None, positiveSide=True, smoothing_width=None)

 
Makes a smooth characteristic function of the region phi(x)>contour if positiveSide and phi(x)<contour otherwise.
Parameters:
  • phi - level set function to be used. If not present the current level set is used.
  • smoothing_width - width of the smoothing zone relative to mesh size. If not present the initial value of smooth is used.

update(self, dt)

 
Sets a new velocity and updates the level set function.
Parameters:
  • dt - time step forward

update_parameter(self, param_neg=-1, param_pos=1, phi=None, smoothing_width=None)

 
Creates a smoothed function with param_neg where phi<0 and param_pos where phi>0 which is smoothed over a length smoothing_width across the interface.
Parameters:
  • smoothing_width - width of the smoothing zone relative to mesh size. If not present the initial value of smooth is used.

update_parameter_sharp(self, param_neg=-1, param_pos=1, phi=None)

 
Creates a function with param_neg where phi<0 and param_pos where phi>0 (no smoothing).
Parameters:
  • param_neg - value of parameter on the negative side (phi<0)
  • param_pos - value of parameter on the positive side (phi>0)
  • phi - level set function to be used. If not present the current level set is used.

update_phi(self, velocity, dt)

 

Updates phi under the presence of a velocity field.

If dt is small this call is equivalent to:

dt=LevelSet.getTimeStepSize(velocity)
phi=LevelSet.update(dt)

otherwise substepping is used.

Parameters:
  • velocity - velocity field
  • dt - time step forward

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