Source code for pygeo.geo_utils.ffd_generation

import numpy as np


[docs]def write_wing_FFD_file(fileName, slices, N0, N1, N2, axes=None, dist=None): """ This function can be used to generate a simple FFD. The FFD can be made up of more than one volume, but the volumes will be connected. It is meant for doing simple wing FFDs. Parameters ---------- fileName : str Name of output file. File is written in plot3d format. slices : numpy array of (Nvol+1, 2, 2, 3) Array of slices. Each slice should contain four points in 3D that will be the corners of the FFD on that slice. If the zeroth dimension size is greater than 2, then multiple volumes will be created, connected by the intermediate slice. N0 : integer or list Number of points to distribute along the zeroth dimension (along the slice direction). N1 : integer or list Number of points to distribute along the first dimension. N2 : integer or list Number of points to distribute along the second dimension. axes : list of ['i', 'j', 'k'] in arbitrary order The user can interchange which index of the FFD corresponds with each dimension of slices. By default 'k' -> 0, 'j' -> 1, 'i' -> 2. dist : list For each volume, the user can specify the distribution of points along each dimension. Options include: - linear - cosine - left (tighter spacing on the left side) - right (tighter spacing on the other left side) Examples -------- This is an example of two volumes: .. code-block:: python axes = ['k', 'j', 'i'] slices = np.array([ # Slice 1 [[[0, 0, 0], [1, 0, 0]], [[0, 0.2, 0], [1, 0.2, 0]]], # Slice 2 [[[0, 0, 2], [1, 0, 2]], [[0, 0.2, 2], [1, 0.2, 2]]], # Slice 3 [[[0.5, 0, 6], [1, 0, 6]], [[0.5, 0.2, 6], [1, 0.2, 6]]], ]) N0 = 5 N1 = 2 N2 = 8 dist = [ ['left', 'linear', 'linear'], ['cosine', 'linear', 'right'] ] """ Nvol = slices.shape[0] - 1 if axes is None: axes = ["k", "j", "i"] if dist is None: dist = [["linear", "linear", "linear"]] * Nvol assert len(dist) == Nvol # Make sure the sizes are the right type in each dimension. If an integer is # given, use that same size for every volume. size = [N0, N1, N2] for iVol, item in enumerate(size): if isinstance(item, int): size[iVol] = [item] * Nvol elif not isinstance(item, list): print("Incorrect type for N0, N1, or N2.") assert len(size[iVol]) == Nvol N0, N1, N2 = size f = open(fileName, "w") f.write(f"{Nvol}\n") def getDistribution(distIn, N): if not isinstance(distIn, str): assert len(distIn) == N dist = distIn.copy() elif distIn == "linear": dist = np.linspace(0, 1, N) elif distIn == "cosine": dist = (1 - np.cos(np.linspace(0, np.pi, N))) / 2.0 elif distIn == "left": dist = np.linspace(0, 1, N) ** (3.0 / 2.0) elif distIn == "right": dist = np.linspace(0, 1, N) ** (2.0 / 3.0) return dist for i in range(Nvol): size = [N0[i], N1[i], N2[i]] Ni = size[axes.index("i")] Nj = size[axes.index("j")] Nk = size[axes.index("k")] f.write("%d\t%d\t%d\n" % (Ni, Nj, Nk)) for iVol in range(Nvol): size = [N0[iVol], N1[iVol], N2[iVol]] Ni = size[axes.index("i")] Nj = size[axes.index("j")] Nk = size[axes.index("k")] # Get distributions for each axis d0 = getDistribution(dist[iVol][0], size[0]) d1 = getDistribution(dist[iVol][1], size[1]) d2 = getDistribution(dist[iVol][2], size[2]) # Initialize coordinate arrays X = np.zeros(size + [3]) for j in range(size[0]): P = slices[iVol, 0, 0] + np.outer(d0, (slices[iVol + 1, 0, 0] - slices[iVol, 0, 0]))[j] Q = slices[iVol, 0, 1] + np.outer(d0, (slices[iVol + 1, 0, 1] - slices[iVol, 0, 1]))[j] R = slices[iVol, 1, 0] + np.outer(d0, (slices[iVol + 1, 1, 0] - slices[iVol, 1, 0]))[j] S = slices[iVol, 1, 1] + np.outer(d0, (slices[iVol + 1, 1, 1] - slices[iVol, 1, 1]))[j] for k in range(size[1]): U = P + np.outer(d1, (R - P))[k] V = Q + np.outer(d1, (S - Q))[k] X[j, k] = U + np.outer(d2, (V - U)) for dim in range(3): line = "" for k in range(Nk): for j in range(Nj): for i in range(Ni): idc = [-1, -1, -1] idc[axes.index("i")] = i idc[axes.index("j")] = j idc[axes.index("k")] = k line += f"{X[idc[0], idc[1], idc[2], dim]: .4e}\t" if len(line) + 11 > 80: f.write(line + "\n") line = "" if len(line) > 0: f.write(line + "\n") f.close()
[docs]def createFittedWingFFD(surf, surfFormat, outFile, leList, teList, nSpan, nChord, absMargins, relMargins, liftIndex): """ Generates a wing FFD with chordwise points that follow the airfoil geometry. Parameters ---------- surf : pyGeo object or list or str The surface around which the FFD will be created. See the documentation for :meth:`pygeo.DVConstraints.setSurface` for details. surfFormat : str The surface format. See the documentation for :meth:`pygeo.DVConstraints.setSurface` for details. outFile : str Name of output file written in PLOT3D format. leList : list or array List or array of points (of size Nx3 where N is at least 2) defining the 'leading edge'. teList : list or array Same as leList but for the trailing edge. nSpan : int or list of int Number of spanwise sections in the FFD. Use a list of length N-1 to specify the number for each segment defined by leList and teList and to precisely match intermediate locations. nChord : int Number of chordwise points in the FFD. absMargins : list of float List with 3 items specifying the absolute margins in the [chordwise, spanwise, thickness] directions. This is useful for areas where the relative margin is too small, such as the trailing edge or wing tip. The total margin is the sum of the absolute and relative margins. relMargins : list of float List with 3 items specifying the relative margins in the [chordwise, spanwise, thickness] directions. Relative margins are applied as a fraction of local chord, wing span, and local thickness. The total margin is the sum of the absolute and relative margins. liftIndex : int Index specifying which direction lift is in (same as the ADflow option). Either 2 for the y-axis or 3 for the z-axis. This is used to determine the wing's spanwise direction. Examples -------- >>> CFDSolver = ADFLOW(options=aeroOptions) >>> surf = CFDSolver.getTriangulatedMeshSurface() >>> surfFormat = "point-vector" >>> outFile = "wing_ffd.xyz" >>> nSpan = [4, 4] >>> nChord = 8 >>> relMargins = [0.01, 0.001, 0.01] >>> absMargins = [0.05, 0.001, 0.05] >>> liftIndex = 3 >>> createFittedWingFFD(surf, surfFormat, outFile, leList, teList, nSpan, nChord, absMargins, relMargins, liftIndex) """ # Import inside this function to avoid circular imports from pygeo import DVConstraints # Set the triangulated surface in DVCon DVCon = DVConstraints() DVCon.setSurface(surf, surfFormat=surfFormat) # Get the surface intersections; surfCoords has dimensions [nSpanTotal, nChord, 2, 3] surfCoords = DVCon._generateIntersections(leList, teList, nSpan, nChord, surfaceName="default") nSpanTotal = np.sum(nSpan) # Initialize FFD coordinates to the surface coordinates FFDCoords = surfCoords.copy() # Swap axes to get the FFD coordinates into PLOT3D ordering [x, y, z, 3] FFDCoords = np.swapaxes(FFDCoords, 0, 1) # [nChord, nSpanTotal, 2, 3] if liftIndex == 2: # Swap axes again so that z is the spanwise direction instead of y FFDCoords = np.swapaxes(FFDCoords, 1, 2) # [nChord, 2, nSpanTotal, 3] # Assign coordinates and dimensions in each direction # x is always the chordwise direction leadingEdge = FFDCoords[0, :, :, 0] trailingEdge = FFDCoords[-1, :, :, 0] Nx = nChord # y and z depend on the liftIndex if liftIndex == 2: root = FFDCoords[:, :, 0, 2] tip = FFDCoords[:, :, -1, 2] upperSurface = FFDCoords[:, 0, :, 1] lowerSurface = FFDCoords[:, 1, :, 1] Ny = 2 Nz = nSpanTotal elif liftIndex == 3: root = FFDCoords[:, 0, :, 1] tip = FFDCoords[:, -1, :, 1] upperSurface = FFDCoords[:, :, 1, 2] lowerSurface = FFDCoords[:, :, 0, 2] Ny = nSpanTotal Nz = 2 else: raise ValueError("liftIndex must be 2 (for y-axis) or 3 (for z-axis)") # Add margins to FFD coordinates chordLength = trailingEdge - leadingEdge leadingEdge -= chordLength * relMargins[0] + absMargins[0] trailingEdge += chordLength * relMargins[0] + absMargins[0] span = np.max(tip - root) root -= span * relMargins[1] + absMargins[1] tip += span * relMargins[1] + absMargins[1] thickness = upperSurface - lowerSurface upperSurface += thickness * relMargins[2] + absMargins[2] lowerSurface -= thickness * relMargins[2] + absMargins[2] # Write FFD file f = open(outFile, "w") f.write("1\n") f.write(f"{Nx} {Ny} {Nz}\n") for ell in range(3): for k in range(Nz): for j in range(Ny): for i in range(Nx): f.write("%.15f " % (FFDCoords[i, j, k, ell])) f.write("\n") f.close()