Example #1
0
def getSpectraAndDisp(k0, nK, nW, root, comp=0):
    files = glob(root)
    numFiles = len(files)

    d = pg.GData(files[0])
    dg = pg.GInterpNodal(d, 2, 'ns')
    x, val = dg.interpolate(0)
    evolution = np.zeros((numFiles, len(x[0])))
    spectrum = np.zeros((numFiles, nK))
    t = np.zeros(numFiles)
    for i, f in enumerate(files):
        d = pg.GData(f)
        t[i] = d.time
        dg = pg.GInterpNodal(d, 2, 'ns')
        x, val = dg.interpolate(comp)

        evolution[i, :] = val

        valf = fftpack.fft(val)
        spectrum[i, :] = np.abs(valf[1:(nK + 1)])**2
    k = fftpack.fftfreq(len(val), x[0][1] - x[0][0])
    k = 2 * np.pi * k[1:(nK + 1)] / k0
    x = x[0] * k0 / 2 / np.pi

    disp = np.zeros((nW, nK))
    for i in range(nK):
        ft = fftpack.fft(spectrum[:, i])
        disp[:, i] = np.abs(ft[1:(nW + 1)])**2
    omega = fftpack.fftfreq(numFiles, t[1] - t[0])
    omega = 2 * np.pi * omega[1:(nW + 1)]

    return x, k, t, omega, evolution, spectrum, disp
def getMoments(polyOrder, pre, numInterp):
    d = postgkyl.GData("%s-sod-shock_neut_M0_1.bp" % pre)
    dg = postgkyl.GInterpModal(d, polyOrder, "ms", numInterp=numInterp)
    X, m0 = dg.interpolate()

    d = postgkyl.GData("%s-sod-shock_neut_M1i_1.bp" % pre)
    dg = postgkyl.GInterpModal(d, polyOrder, "ms", numInterp=numInterp)
    X, m1i = dg.interpolate()

    d = postgkyl.GData("%s-sod-shock_neut_M2_1.bp" % pre)
    dg = postgkyl.GInterpModal(d, polyOrder, "ms", numInterp=numInterp)
    X, m2 = dg.interpolate()

    d = postgkyl.GData("%s-sod-shock_neut_M3i_1.bp" % pre)
    dg = postgkyl.GInterpModal(d, polyOrder, "ms", numInterp=numInterp)
    X, m3i = dg.interpolate()

    u = m1i / m0  # Velocity.
    nvt2 = m2 - m0 * u**2  # Pressure (density*temperature).
    q = m3i - (3 * u * m2 - 3 * u**2 * m1i + u**3 * m0
               )  # Plasma-frame heat-flux.

    Xn = X[0]
    dx = Xn[1] - Xn[0]
    # Cell-center coordinates.
    Xc = linspace(Xn[0] + 0.5 * dx, Xn[-1] - 0.5 * dx, Xn.shape[0] - 1)

    return Xc, m0, u, nvt2, q
Example #3
0
def calcEnergyError(pre, p):
    # Inputs:
    # pre - prefix for file name.
    # p - polynomial order (used for assisting in distinguishing between different prefixes).
    # Outputs:
    # t - array of time data.
    # err - normalized error ( abs(err - err[0])/err[0] ) in the total energy.

    # Read in electron data.
    d = postgkyl.GData("%s-conservation-test-%s_elc_intM2Thermal.bp" %
                       (pre, p))
    elcM2Thermal = 0.5 * elcMass * d.getValues()
    d = postgkyl.GData("%s-conservation-test-%s_elc_intM2Flow.bp" % (pre, p))
    elcM2Flow = 0.5 * elcMass * d.getValues()
    # Read in proton data.
    d = postgkyl.GData("%s-conservation-test-%s_ion_intM2Thermal.bp" %
                       (pre, p))
    ionM2Thermal = 0.5 * ionMass * d.getValues()
    d = postgkyl.GData("%s-conservation-test-%s_ion_intM2Flow.bp" % (pre, p))
    ionM2Flow = 0.5 * ionMass * d.getValues()
    # Read in electromagnetic field data.
    d = postgkyl.GData("%s-conservation-test-%s_fieldEnergy.bp" % (pre, p))
    fieldEnergy = 0.5 * epsilon0 * d.getValues()

    t = d.getGrid()[0]
    err = calcNormError(elcM2Flow[:, 0] + elcM2Thermal[:, 0] +
                        ionM2Flow[:, 0] + ionM2Thermal[:, 0] +
                        fieldEnergy[:, 0])

    return t, err
def getMoments(polyOrder, pre, numInterp):
    d = postgkyl.GData("%s-sod-shock_neut_M0_1.bp" % pre)
    dg = postgkyl.GInterpModal(d, polyOrder, "ms", numInterp=numInterp)
    X, m0 = dg.interpolate()

    d = postgkyl.GData("%s-sod-shock_neut_M1i_1.bp" % pre)
    dg = postgkyl.GInterpModal(d, polyOrder, "ms", numInterp=numInterp)
    X, m1i = dg.interpolate()

    d = postgkyl.GData("%s-sod-shock_neut_M2_1.bp" % pre)
    dg = postgkyl.GInterpModal(d, polyOrder, "ms", numInterp=numInterp)
    X, m2 = dg.interpolate()

    d = postgkyl.GData("%s-sod-shock_neut_M3i_1.bp" % pre)
    dg = postgkyl.GInterpModal(d, polyOrder, "ms", numInterp=numInterp)
    X, m3i = dg.interpolate()

    u = m1i/m0 # velocity
    nvt2 = m2 - m0*u**2 # ptcl internal energy
    q = m3i - (3*u*m2 - 3*u**2*m1i + u**3*m0) # heat-flux

    Xn = X[0]; dx = Xn[1]-Xn[0]
    # cell-center coordinates
    Xc = linspace(Xn[0]+0.5*dx, Xn[-1]-0.5*dx, Xn.shape[0]-1)

    return Xc, m0, u, nvt2, q
def calcEnergyError(pre):
    d = postgkyl.GData("%s-relax_neut_intM2Thermal.bp" % pre)
    m2Thermal = d.getValues()
    d = postgkyl.GData("%s-relax_neut_intM2Flow.bp" % pre)
    m2Flow = d.getValues()

    t = d.getGrid()[0]
    err = calcNormError(m2Flow + m2Thermal)

    return t, err
def calcMeanSpect(fn, lo, up):
    d = postgkyl.GData("%s_00%d.bp" % (fn, lo))
    s = d.getValues()
    g = d.getGrid()
    dx = g[0][1] - g[0][0]
    gc = linspace(g[0][0] + 0.5 * dx, g[0][-1] - 0.5 * dx, g[0].shape[0] - 1)

    for i in range(lo + 1, up + 1):
        d = postgkyl.GData("%s_00%d.bp" % (fn, i))
        s = s + d.getValues()

    return gc, sqrt(s / (up - lo + 1))
Example #7
0
def calc_ke_dke(root_file_name, initFrame, finalFrame, dim, Vol):
    #function to calculate all the total kinetic energy and the rate of dissipation of KE
    #root_file_name is the name of the file before the numbers start
    #initFrame is the first frame and finalFrame is the final frame
    #dim gives the dimension of the simulation (2 = 2D, 3 = 3D)
    #Vol = the volume of the grid
    #returns the kinetic energy and dissipation of KE

    #calculate integrated kinetic energy
    ke = np.zeros((1, (finalFrame - initFrame + 1)))
    dEk = ke
    f = postgkyl.GData(root_file_name + str(initFrame) + '.bp')
    grid = f.getGrid()
    dx = grid[0][1] - grid[0][0]
    dy = grid[1][1] - grid[1][0]
    dt = (finalTime - initTime + 1) / (finalFrame - initFrame + 1)
    r = 0

    if dim == 3:
        dz = grid[2][1] - grid[2][0]
    elif dim == 2:
        dz = 1

    for c in range(initFrame, finalFrame + 1):
        frame = postgkyl.GData(root_file_name + "%d.bp" % c)
        data = frame.getValues()
        if dim == 2:
            rho = data[:, :, 0]
            px = data[:, :, 1]
            py = data[:, :, 2]
            pz = data[:, :, 3]
        elif dim == 3:
            rho = data[:, :, :, 0]
            px = data[:, :, :, 1]
            py = data[:, :, :, 2]
            pz = data[:, :, :, 3]

        u = px / (rho * V0)
        v = py / (rho * V0)
        w = pz / (rho * V0)

        e = rho * (u**2 + v**2 + w**2)
        ke[0, r] = np.sum(e, axis=(0, 1, 2)) * dx * dy * dz * Vol
        r += 1

    r = 0
    for i in range(initFrame, finalFrame - 1):
        dEk[0, r] = -(ke[0, i + 1] - ke[0, i]) / dt
        r += 1

    return ke, dEk
def calcEnergyError(pre):
    d = postgkyl.GData("%s-sonic-sod-shock_neut_intM2Thermal.bp" % pre)
    m2Thermal = d.getValues()
    d = postgkyl.GData("%s-sonic-sod-shock_neut_intM2Flow.bp" % pre)
    m2Flow = d.getValues()

    t = d.getGrid()[0]
    eErr = calcNormError(m2Flow + m2Thermal)

    d = postgkyl.GData("%s-sonic-sod-shock_neut_intM1i.bp" % pre)
    m1i = d.getValues()
    mErr = calcNormError(m1i)

    return t, eErr, mErr
Example #9
0
def getJ(fr):
    data = pg.GData("%s_elc_M1i_%d.bp" % (baseNm, fr))
    dg = pg.data.GInterpModal(data, 2, "ms")
    XX, m1e = dg.interpolate()
    
    data = pg.GData("%s_ion_M1i_%d.bp" % (baseNm, fr))
    dg = pg.data.GInterpModal(data, 2, "ms")
    XX, m1i = dg.interpolate()

    Jg = 0.159*ones(Ji.shape, float)

    Xn = XX[0]; dx = Xn[1]-Xn[0]
    Xc = linspace(Xn[0]+0.5*dx, Xn[-1]-0.5*dx, Xn.shape[0]-1)

    return Xc, m1i, -m1e+Jg
Example #10
0
def getRawGrid(dataFile, **opKey):
    pgData = pg.GData(dataFile)  #.Read data with pgkyl.
    dimOut = pgData.getNumDims()
    xNodal = pgData.getGrid()

    #.If desired, output cell center values of grid coordinates instead of nodal coordinates.
    if 'location' in opKey:
        if opKey['location'] == 'center':
            xOut = [[] for i in range(dimOut)]
            for i in range(dimOut):
                nNodes = np.shape(xNodal[i])[0]
                xOut[i] = np.zeros(nNodes - 1)
                xOut[i] = np.multiply(
                    0.5, xNodal[i][0:nNodes - 1] + xNodal[i][1:nNodes])
        else:
            xOut = xNodal
    else:
        xOut = xNodal

    nxOut = np.zeros(dimOut, dtype='int')
    lxOut = np.zeros(dimOut, dtype='double')
    dxOut = np.zeros(dimOut, dtype='double')
    for i in range(dimOut):
        nxOut[i] = np.size(xOut[i])
        lxOut[i] = xOut[i][-1] - xOut[i][0]
        dxOut[i] = xOut[i][1] - xOut[i][0]

    return xOut, dimOut, nxOut, lxOut, dxOut
Example #11
0
    def test_LoadBpFrame(self):
        data = pg.GData('data/frame_0.bp')

        nd = data.getNumDims()
        assert (isinstance(nd, int))
        self.assertEqual(nd, 2)

        nc = data.getNumComps()
        assert (isinstance(nc, int))
        self.assertEqual(nc, 8)

        lo, up = data.getBounds()
        assert (isinstance(lo, np.ndarray))
        assert (isinstance(up, np.ndarray))
        self.assertEqual(len(lo), 2)
        self.assertEqual(len(up), 2)

        nc = data.getNumCells()
        assert (isinstance(nc, np.ndarray))
        assert (isinstance(nc[0], np.int64))
        assert (isinstance(nc[1], np.int64))
        self.assertEqual(nc[0], 64)
        self.assertEqual(nc[1], 32)

        grid = data.peakGrid()
        assert (isinstance(grid, list))
        self.assertEqual(len(grid), 2)
        assert (isinstance(grid[0], np.ndarray))
        assert (isinstance(grid[1], np.ndarray))
        self.assertEqual(grid[0].shape, (64, ))
        self.assertEqual(grid[1].shape, (32, ))

        values = data.peakValues()
        assert (isinstance(values, np.ndarray))
        self.assertEqual(values.shape, (64, 32, 8))
Example #12
0
    def test_LoadBpHistory(self):
        data = pg.GData('data/hist_')

        nd = data.getNumDims()
        assert (isinstance(nd, int))
        self.assertEqual(nd, 1)

        nc = data.getNumComps()
        assert (isinstance(nc, int))
        self.assertEqual(nc, 8)

        lo, up = data.getBounds()
        assert (isinstance(lo, np.ndarray))
        assert (isinstance(up, np.ndarray))
        self.assertEqual(len(lo), 1)
        self.assertEqual(len(up), 1)

        nc = data.getNumCells()
        assert (isinstance(nc, np.ndarray))
        assert (isinstance(nc[0], np.int64))
        self.assertEqual(nc[0], 7641)

        grid = data.peakGrid()
        assert (isinstance(grid, list))
        self.assertEqual(len(grid), 1)
        assert (isinstance(grid[0], np.ndarray))
        self.assertEqual(grid[0].shape, (7641, ))

        values = data.peakValues()
        assert (isinstance(values, np.ndarray))
        self.assertEqual(values.shape, (7641, 8))
Example #13
0
def getGrid(dataFile, p, basisType, **opKey):
    pgData = pg.GData(dataFile)  #.Read data with pgkyl.
    pgInterp = pg.GInterpModal(pgData, p, basisType)  #.Interpolate data.
    xNodal, dataInterp = pgInterp.interpolate()
    dimOut = np.shape(xNodal)[0]  #.Number of dimensions in data.

    #.If desired, output cell center values of grid coordinates instead of nodal coordinates.
    if 'location' in opKey:
        if opKey['location'] == 'center':
            xOut = [[] for i in range(dimOut)]
            for i in range(dimOut):
                nNodes = np.shape(xNodal[i])[0]
                xOut[i] = np.zeros(nNodes - 1)
                xOut[i] = np.multiply(
                    0.5, xNodal[i][0:nNodes - 1] + xNodal[i][1:nNodes])
        else:
            xOut = xNodal
    else:
        xOut = xNodal

    nxOut = np.zeros(dimOut, dtype='int')
    lxOut = np.zeros(dimOut, dtype='double')
    dxOut = np.zeros(dimOut, dtype='double')
    for i in range(dimOut):
        nxOut[i] = np.size(xOut[i])
        lxOut[i] = xOut[i][-1] - xOut[i][0]
        dxOut[i] = xOut[i][1] - xOut[i][0]
    return xOut, dimOut, nxOut, lxOut, dxOut
Example #14
0
def getDist(pre, fr):
    d = postgkyl.GData("%s-bi-maxwellian-relax_neut_%d.bp" % (pre, fr))
    dg = postgkyl.GInterpModal(d, 2, "ms")
    XX, fv = dg.interpolate()

    X, V = meshgrid(XX[1], XX[2])
    return X, V, fv
def plotFig(nr,nc,i,fr, showX=False):
    print("Working on %d ..." % i)
    data = pg.GData("s3-oscc-E_ions_%d.bp" % fr)
    dg = pg.data.GInterpModal(data, 2, "ms")
    XX, q = dg.interpolate()

    tm = data.time
    wx, wy = wR(tm)

    qEx = fexact(wx, wy)

    f = subplot(nr,nc,i)    
    pcolormesh(XX[1], XX[2], transpose(q[3,:,:,0]))
    plot(WX, WY, 'w', linewidth=0.5)
    if showX:
        xlabel("$v_x$")
    
    ylabel('$v_y$')
    grid()        
    axis('image')

    f = subplot(nr,nc,i+1)
    pcolormesh(VX, VY, qEx)
    plot(WX, WY, 'w', linewidth=0.5)
    if showX:
        xlabel("$v_x$")
    grid()
    axis('image')
Example #16
0
def getInterpData(dataFile, p, basisType, **opKey):
    pgData = pg.GData(dataFile)  #.Read data with pgkyl.
    pgInterp = pg.GInterpModal(pgData, p, basisType)  #.Interpolate data.
    if 'comp' in opKey:
        xOut, dataOut = pgInterp.interpolate(opKey['comp'])
    else:
        xOut, dataOut = pgInterp.interpolate()
    return dataOut
Example #17
0
def plotP(p, fName):
    for i in range(1, 11):
        print("Woroking on %s_%d.bp ... " % (fName, i))
        data = pg.GData("%s_%d.bp" % (fName, i))
        T = data.peakGrid()
        v = data.peakValues()
        tp, vp = mkPoincare(T[0], v)
        p.scatter(2 * pi * array(tp) / tper, array(vp), 0.1, marker='.')
Example #18
0
def calcMomentumError(pre):
    d = postgkyl.GData("%s-bi-maxwellian-relax_neut_intM1i_" % pre)
    m1i = d.getValues()

    t = d.getGrid()[0]
    err1 = calcNormError(m1i[:, 0])
    err2 = calcNormError(m1i[:, 1])

    return t, err1, err2
def getEntropy(polyOrder, pre):
    svals = zeros((100, ), float)
    for i in range(0, 100):
        d = postgkyl.GData("%s-relax_neut_%d.bp" % (pre, i))
        dg = postgkyl.GInterpModal(d, polyOrder, "ms")
        XX, fv = dg.interpolate()
        svals[i] = calcEntropy(XX[0], XX[1], fv)

    return svals
def plotFig(i, fr):
    print("Working on %d ..." % i)
    data = pg.GData("c4-oscc-E_ions_%d.bp" % fr)
    dg = pg.data.GInterpModal(data, 2, "ms")
    XX, q = dg.interpolate()
    nx2 = int(q.shape[0] / 2)
    nvx2 = int(q.shape[1] / 2)

    return q[nx2, nvx2, :, 0]
def calcMomentumError(pre, p):
    # Inputs:
    # pre - prefix for file name.
    # p - polynomial order (used for assisting in distinguishing between different prefixes).
    # Outputs:
    # t - array of time data.
    # err - normalized error ( abs(err - err[0])/err[0] ) in the total momentum.

    # Read in electron data.
    d = postgkyl.GData("%s-conservation-test-%s_elc_intM1i.bp" % (pre, p))
    elcM1i = elcMass * d.getValues()
    # Read in proton data.
    d = postgkyl.GData("%s-conservation-test-%s_ion_intM1i.bp" % (pre, p))
    ionM1i = ionMass * d.getValues()

    t = d.getGrid()[0]
    err = calcNormError(elcM1i[:, 0] + ionM1i[:, 0])

    return t, err
def plotFig(i,fr):
    print("Working on %d ..." % i)
    data = pg.GData("c5-oscc-E_ions_%d.bp" % fr)
    dg = pg.data.GInterpModal(data, 2, "ms")
    XX, q = dg.interpolate()
    qsum = sum(q,axis=0)

    nvx2 = int(q.shape[1]/2)

    return qsum[nvx2,:].squeeze()
Example #23
0
def plotFig(i, fr):
    print("Working on %d ..." % i)
    figure(i, figsize=(14, 8))
    data_fieldEnergy = pg.GData("kink_fieldEnergy_")
    t = data_fieldEnergy.getGrid()[0]
    fieldEnergy = data_fieldEnergy.getValues()
    ExEnergy = 0.5 * fieldEnergy[:, 0]

    omegaCi = 0.0055277079839257
    t = t * 0.0055277079839257
    #param, R2, N = fitGrowth(t[40000:50000], ExEnergy[40000:50000])
    subplot(1, 2, 1)
    semilogy(t, ExEnergy, "k")
    xlabel("$t (\Omega_{ci}^{-1})$")
    ylabel("$\int E_x^2$")
    xlim(0, 8)
    ylim(1e-12, 1e-2)

    data_field = pg.GData("kink_field_%d.bp" % fr)
    dg_field = pg.data.GInterpModal(data_field, 2, "ms")
    XX, Ex = dg_field.interpolate(0)
    #center the grid values
    for d in range(2):
        XX[d] = 0.5 * (XX[d][:-1] + XX[d][1:])
    #normalization for electric field
    ionMass = 36
    norm = (omegaCi * ionMass)**2 / math.sqrt(ionMass)
    #computing ion larmor radius
    vtIon = 0.0316227833333333
    rhoi = vtIon / omegaCi
    subplot(1, 2, 2)
    pcolormesh(XX[0] / rhoi,
               XX[1] / rhoi,
               Ex[:, :, 0].transpose() / norm,
               cmap="seismic",
               shading="gouraud")
    colorbar(label="$E_x$")
    xlabel(r"$X(\rho_i)$")
    ylabel(r"$Y(\rho_i)$")
    title(r"$t=6 \Omega_{ci}^{-1}$")

    tight_layout()
    savefig("lhdi-ex-energy-and-ex.pdf")
def plotFig1D(i, lbl):
    print("Working on %d ..." % i)
    
    data = pg.GData("c6-oscc-E_ions_%d.bp" % i)
    dg = pg.data.GInterpModal(data, 2, "ms")
    XX, q = dg.interpolate()
    numCells = q.shape
    qSum = sum(q, axis=0)*(2.0*pi)/numCells[0]

    plot(XX[1], qSum[:,int(numCells[2]/2),0], label=lbl)
    grid()
Example #25
0
def getExpRecon(pre, fr):
    d = postgkyl.GData("%s-relax_neut_%d.bp" % (pre, fr))
    q = d.getValues()
    f0 = q[0, :, 0]
    f1 = q[0, :, 2]

    gcoeff = zeros((f0.shape[0], 2), float)
    for i in range(f0.shape[0]):
        gcoeff[i][0], gcoeff[i][1] = fitExp(f0[i], f1[i])

    return gcoeff
Example #26
0
def calcL2Error(pre, p):
    # Inputs:
    # pre - prefix for file name.
    # p - polynomial order (used for assisting in distinguishing between different prefixes).
    # Outputs:
    # t - array of time data.
    # err_elcL2 - normalized error ( abs(err - err[0])/err[0] ) in the electron L^2 norm (f_e^2).
    # ion_elcL2 - normalized error ( abs(err - err[0])/err[0] ) in the proton L^2 norm (f_p^2).

    # Read in electron data.
    d = postgkyl.GData("%s-conservation-test-%s_elc_intL2.bp" % (pre, p))
    elcL2 = d.getValues()
    # Read in proton data.
    d = postgkyl.GData("%s-conservation-test-%s_ion_intL2.bp" % (pre, p))
    ionL2 = d.getValues()

    t = d.getGrid()[0]
    err_elcL2 = calcNormError(elcL2[:, 0])
    err_ionL2 = calcNormError(ionL2[:, 0])

    return t, err_elcL2, err_ionL2
Example #27
0
def getPhi(fr):
    data = pg.GData("n1-es-buneman_field_%d.bp" % fr)
    dg = pg.data.GInterpModal(data, 2, "ms")
    XX, E = dg.interpolate()
    X1 = XX[0]
    dx = X1[1] - X1[0]

    phi = numpy.zeros((E.shape[0] + 1, 1), numpy.float)
    for i in range(1, phi.shape[0]):
        phi[i] = phi[i - 1] - dx * E[i - 1]

    return phi - 0 * min(phi)
def plotFig(nr,nc,i,fr):
    print("Working on %d ..." % i)
    
    data = pg.GData("c6-oscc-E_ions_%d.bp" % fr)
    dg = pg.data.GInterpModal(data, 2, "ms")
    XX, q = dg.interpolate()
    qSum = sum(q, axis=0)

    subplot(nr,nc,i)
    pcolormesh(XX[1], XX[2], transpose(qSum[:,:,0]))
    grid()
    axis('image')
def getData(i):
    #print("Working on %d ..." % i)
    data = pg.GData("s4-oscc-E_ions_%d.bp" % i)
    dg = pg.data.GInterpModal(data, 2, "ms")
    XX, q = dg.interpolate()
    nx, nvx, nvy = q.shape[0], q.shape[1], q.shape[2]
    
    qMid = q[int(nx/2),:,int(nvy/2)]

    tm = data.time
    tm = tm - tper*floor(tm/tper)

    return tm, qMid
def plotFig(i):
    print("Working on %d ..." % i)
    
    data = pg.GData("c6-oscc-E_ions_M0_%d.bp" % i)
    dg = pg.data.GInterpModal(data, 2, "ms")
    XX, q0 = dg.interpolate()

    data = pg.GData("c6-oscc-E_ions_M1i_%d.bp" % i)
    dg = pg.data.GInterpModal(data, 2, "ms")
    XX, nux = dg.interpolate(0)
    XX, nuy = dg.interpolate(1)    
    ux = nux/q0
    uy = nuy/q0
    
    data = pg.GData("c6-oscc-E_ions_M2_%d.bp" % i)
    dg = pg.data.GInterpModal(data, 2, "ms")
    XX, q2 = dg.interpolate()

    dx = 1/q2.shape[0]

    vt = (q2-q0*(ux**2+uy**2))*0.5
    return dx*vt.sum()