fluid.py

from ctypes import *
import numpy
import signal
import os

dir_path = os.path.dirname(os.path.dirname(os.path.dirname(os.path.realpath(__file__))))
lib = CDLL(os.path.join(dir_path,"libmbfluid2.so"))

signal.signal(signal.SIGINT, signal.SIG_DFL)


BNDCB = CFUNCTYPE(None,c_int,POINTER(c_double),POINTER(c_double))
class StrongBoundary(Structure):
    _fields_ = [("tag",c_char_p),("field",c_int),("apply",BNDCB)]

class fluid_problem :

    def __init__(self, mesh_file_name, g, mu, rho, epsilon, strong_boundaries):
        nsb = len(strong_boundaries)
        class Bnd :
            def __init__(self, b) :
                self._b = b
            def apply(self, n, xp, vp) :
                x = numpy.frombuffer(cast(xp, POINTER(int(n)*2*c_double)).contents).reshape([n,2])
                v = numpy.frombuffer(cast(vp, POINTER(int(n)*c_double)).contents)
                if callable(self._b) :
                    v[:] = self._b(x)
                else :
                    v[:] = self._b

        asb = (StrongBoundary*nsb)(*[StrongBoundary(i[0].encode(),i[1],BNDCB(Bnd(i[2]).apply)) for i in strong_boundaries])
        self.asb = asb
        lib.fluid_problem_new.restype = c_void_p
        self._fp = c_void_p(lib.fluid_problem_new(mesh_file_name.encode(), c_double(g), c_double(mu), c_double(rho), c_double(epsilon), nsb, asb))
        if self._fp == None :
            raise NameError("cannot create fluid problem")

    def __del__(self):
        if(self._fp != None) :
            lib.fluid_problem_free(self._fp)

    def adapt_mesh(self, lcmax, lcmin, n_el, alpha, notComputeEpsilon) :
        lib.fluid_problem_adapt_mesh(self._fp, c_double(lcmax), c_double(lcmin), c_double(n_el), c_double(alpha), c_int(notComputeEpsilon))

    def export(self, output_dir, t, it) :
        lib.fluid_problem_export(self._fp, output_dir.encode(), c_double(t), c_int(it))

    def export_vtk(self, output_dir, t, it) :
        lib.fluid_problem_export_vtk(self._fp, output_dir.encode(), c_double(t), c_int(it))

    def import_vtk(self, filename) :
        lib.fluid_problem_import_vtk(self._fp, filename.encode())

    def compute_node_force(self, dt) :
        forces = numpy.ndarray([self.n_particles,2],"d",order="C")
        lib.fluid_problem_compute_node_particle_force(self._fp, c_double(dt), c_void_p(forces.ctypes.data))
        return forces

    def implicit_euler(self, dt) :
        return lib.fluid_problem_implicit_euler(self._fp, c_double(dt))

    def set_particles(self, mass, volume, position, velocity):
        def np2c(a) :
            tmp = numpy.require(a,"float","C")
            r = c_void_p(tmp.ctypes.data)
            r.tmp = tmp
            return r
        self.n_particles = mass.shape[0]
        lib.fluid_problem_set_particles(self._fp,c_int(mass.shape[0]),np2c(mass),np2c(volume),np2c(position),np2c(velocity),None)


    def particle_element_id(self) :
        f = getattr(lib,"fluid_problem_particle_element_id")
        f.restype = c_void_p
        fs = getattr(lib,"fluid_problem_n_particles")
        fs.restype = c_int
        ptr = f(self._fp)
        size = fs(self._fp)
        buf = (size*c_int).from_address(ptr)
        return numpy.ctypeslib.as_array(buf)