Magnus Force, Drag force , Serve Ball Trajectory - python

I am trying to put into this code. Main focus for the code would be to combine all of the forces, hitting at various launch angles and print out the graph of figure 42.3.
from numpy import *
from matplotlib import*
from matplotlib.pyplot import *
from __future__ import division
Basic info
Dimeter = 0.067
r = (Dimeter/2) # radius of sphere (meters)
s = 1.0 # spin in revolutions per second (positive is backspin)
p = 1.225 # air density in kg/m^3
dragCoef = 0.5 # drag coefficient
m = 0.0585 # mass of the ball in kilograms
g = 9.82 # gravitational constant
dt = 0.01
A = (pi*r**2)
Cd = 0.5
Cl = 1.5
v = 30
t = 0.470
n= (t/dt)
a = zeros(n)
v = zeros(n)
x = zeros(n)
Fg = zeros(n)
Fd = zeros(n)
t = zeros(n)
v[0] = 0
x[0] = 0
i = 0
A while loop to add Forces on the ball
while i <= (n-2):
Fg[i] = (m*g)
Fd[i] = (.5*p*A*Cd*(v[i]**2)*sign(-v[i]))
a[i] = ((Fg[i] + Fd[i]) / m)
v[i+1] = (v[i] + a[i]*dt)
x[i+1] = (x[i] +v[i]*dt +.5*a[i]*(dt**2))
t[i+1] = (t[i] + dt)
i = i+1
Printing out graph
print "My distance is",max(x)-min(x), "meters"
print "At t=", argmax(x)/100, "s"
plot(x,label="position")
legend()

Related

Python function calling with variable vs raw numbers

I am trying to implement a pso algorithm from Wikipedia https://en.wikipedia.org/wiki/Particle_swarm_optimization.
My problem is that when I am calling the cost function with a variable (Gbest), and then manually calling the cost function (with the Gbest data) I get a different output (cost) like the image bellow:
Code fault
I am new to python so thank you for any suggestions.
Here is the complete code:
import matplotlib.pyplot as plt
import numpy as np
from control.matlab import *
A = np.array([[0,0,1],[0,1,0],[1,2,-2]])
B = np.array( [[0],[1],[0]])
C = np.array([[0, 1,0]])
D = np.zeros([C.shape[0],B.shape[1]])
sys = ss(A,B,C,D)
sys_tf = tf(sys)
s = tf('s')
def cost(kp,ki):
global sys_tf, G, y, t, r
G = kp + ki/s
C = feedback(sys_tf*G, 1)
y, t = step(C, linspace(0,100))
r = np.ones(len(t))
return np.sum(y-r)**2
part = 100
ite = 10000
dim = 2
w = 0.001
wdamp = 0.99
phip = 0.9
phig = 0.1
blo, bup = -10,10
x = np.zeros([dim, part])
v = np.zeros([dim, part])
pbest = np.zeros([dim, part])
gbest = np.array([1000000,1000000])
for i in range(part):
for k in range(dim):
x[k][i] = pbest[k][i] = np.random.uniform(blo, bup)
v[k][i] = np.random.uniform(-np.abs(bup - blo), np.abs(bup - blo))
if cost(pbest[0][i], pbest[1][i]) < cost(gbest[0], gbest[1]):
gbest = np.array([pbest[0][i], pbest[1][i]])
for it in range(ite):
for i in range(part):
for k in range(dim):
rp = np.random.uniform(0,1)
rg = np.random.uniform(0,1)
v[k,:] = w*v[k,:] + phip*rp*(pbest[k,:] - x[k,:]) + phig*rg*(gbest[k] - x[k,:])
x[k,:] = x[k,:] + v[k,:]
w = w*wdamp
if cost(x[0][i], x[1][i]) < cost(pbest[0][i], pbest[1][i]):
pbest[:,i] = x[:,i]
if cost(pbest[0][i], pbest[1][i]) < cost(gbest[0], gbest[1]):
gbest = np.array([pbest[0][i], pbest[1][i]])
plt.plot(t, y, 'ro')
plt.plot(t, r, 'x')
plt.pause(0.005)
plt.title(gbest)
print([gbest, cost(gbest[0], gbest[1])])

Why does translation matrix not affect rendering of 3d model in python?

I am very new to coding and decided to start with a 3D engine in python. I followed OLC's tutorial and adapted it for python. However, my translation matrix doesn't seem to be affecting how the model is rendered. Any advice at all, from code improvements, to telling me how bad I am would be much appreciated.
I have tried to re-do the vector multiplication in all sorts of ways, and all kinds of reformatting and re-trying, but I am not even sure what I am looking for in this case. Any help would be much appreciated
As I am new, I apologize for any poor etiquette I may have done on this site.
import math, numpy as np, pygame, sys, os, random, string
from pygame.locals import *
pygame.init()
width,height = 1600,900;cx,cy = width//2,height//2
screen = pygame.display.set_mode((width,height))
clock = pygame.time.Clock()
font = pygame.font.SysFont("Arial", 18)
pygame.display.set_caption('3D Graphics')
def loadObj(filename):
tris = []
verts = []
try:
fp = open(filename, "r")
except:
print("File: "+filename+" not found")
sys.exit(1)
for line in fp:
if line.startswith('#'): continue
values = line.split()
if not values: continue
if values[0] == 'v':
#v = vec3(float(values[1]), float(values[2]), float(values[3]))
#verts.append(vec3(int(values[1]), int(values[2]), int(values[3])))
verts.append(vec3(float(values[1]), float(values[2]), float(values[3]), 0 ))
#verts.append(v)
elif values[0] == 'f':
p = []
for v in values[1:]:
w = v.split("/")
p.append(int(w[0]))
#print(p)
#print(verts[-185])
triTemp = triangle(verts[p[0] - 1], verts[p[1] - 1], verts[p[2]- 1])
tris.append(triTemp)
fp.close()
return tris
class vec3(): #Possibly Obsolete
__slots__ = ['x','y','z','w']
def __init__(self, x, y, z, w):
self.x = x
self.y = y
self.z = z
self.w = w
class triangle():
__slots__ = ['vec1','vec2','vec3']
def __init__(self, vec1, vec2, vec3):
self.vec1 = vec1
self.vec2 = vec2
self.vec3 = vec3
def matrixMakeTranslation(x, y, z):
matrix = np.zeros((4,4))
matrix[0,0] = 1.0
matrix[1,1] = 1.0
matrix[2,2] = 1.0
matrix[3,3] = 1.0
matrix[3,0] = x
matrix[3,1] = y
matrix[3,2] = z
return matrix
def Matrix_MakeRotationX(fAngleRad):
matrix = np.zeros((4,4))
matrix[0,0] = 1.0
matrix[1,1] = (math.cos(fAngleRad * 0.5))
matrix[1,2] = (math.sin(fAngleRad * 0.5))
matrix[2,1] = (-math.sin(fAngleRad * 0.5))
matrix[2,2] = (math.cos(fAngleRad * 0.5))
matrix[3,3] = 1.0
return matrix
def Matrix_MakeRotationZ(fAngleRad):
matrix = np.zeros((4,4))
matrix[0,0] = (math.cos(fAngleRad))
matrix[0,1] = (math.sin(fAngleRad))
matrix[1,0] = (-math.sin(fAngleRad))
matrix[1,1] = (math.cos(fAngleRad))
matrix[2,2] = 1.0
matrix[3,3] = 1.0
return matrix
fNear = float(0.1) #Create the Projection Matrix
fFar = float(1000.0)
fFov = float(90.0)
fAspectRatio = float(height/width)
fFovRad = 1/math.tan(fFov * 0.5 / 180 * math.pi)
projectionMatrix = np.zeros((4,4))
projectionMatrix[0,0] = fAspectRatio * fFovRad
projectionMatrix[1,1] = fFovRad
projectionMatrix[2,2] = fFar / (fFar - fNear)
projectionMatrix[3,2] = float((-fFar * fNear) / (fFar - fNear))
projectionMatrix[2,3] = 1.0
projectionMatrix[3,3] = 0.0
meshname = "teapot.obj" #Load the mesh
tris = loadObj(meshname)
vCamera = np.array([0,0,0,0])
fAngleRad = 0
colour = (255,255,255)
colour2 = (0,0,0)
triProjected = triangle(np.array([0,0,0,0]),np.array([0,0,0,0]),np.array([0,0,0,0])) #These are used later
triTranslalted = triangle(np.array([0,0,0,0]),np.array([0,0,0,0]),np.array([0,0,0,0]))
triTransformed= triangle(np.array([0,0,0,0]),np.array([0,0,0,0]),np.array([0,0,0,0]))
while True: #Begin Loop
for event in pygame.event.get(): #Quit
if event.type == pygame.QUIT: pygame.quit(); sys.exit()
dt = clock.tick()/1000
pygame.display.set_caption('3D Graphics - FPS: %.2f'%int(dt))
print("fps:", clock.get_fps()) #Framerate and caption
pygame.display.update()
screen.fill((0,0,0))
fAngleRad += 0.1
matRotZ = Matrix_MakeRotationZ(fAngleRad * 0.5) #Set up matricies
matRotX = Matrix_MakeRotationX(fAngleRad)
matTrans = matrixMakeTranslation(0.0,0.0,50.0)
matWorld = np.identity(4)
matWorld = matRotZ # matRotX
matWorld = matWorld # matTrans #Seems to be broken. idk why.
for i in tris: #For triangle in all triangles
reDo1 = np.array([i.vec1.x, i.vec1.y, i.vec1.z, i.vec1.w])
reDo2 = np.array([i.vec2.x, i.vec2.y, i.vec2.z, i.vec2.w])
reDo3 = np.array([i.vec3.x, i.vec3.y, i.vec3.z, i.vec3.w])
triTransformed.vec1 = np.matmul(matWorld, reDo1)
triTransformed.vec2 = np.matmul(matWorld, reDo2)
triTransformed.vec3 = np.matmul(matWorld, reDo3)
triProjected.vec1 = np.matmul(projectionMatrix, triTransformed.vec1)
triProjected.vec2 = np.matmul(projectionMatrix, triTransformed.vec2)
triProjected.vec3 = np.matmul(projectionMatrix, triTransformed.vec3)
#Scale Into View
triProjected.vec1[0] += 1.0
triProjected.vec1[1] += 1.0
triProjected.vec2[0] += 1.0
triProjected.vec2[1] += 1.0
triProjected.vec3[0] += 1.0
triProjected.vec3[1] += 1.0
triProjected.vec1[0] *= 0.5 * width
triProjected.vec1[1] *= 0.5 * height
triProjected.vec2[0] *= 0.5 * width
triProjected.vec2[1] *= 0.5 * height
triProjected.vec3[0] *= 0.5 * width
triProjected.vec3[1] *= 0.5 * height
pygame.draw.polygon(screen, colour, [(triProjected.vec1[0], triProjected.vec1[1]),(triProjected.vec2[0], triProjected.vec2[1]),(triProjected.vec3[0], triProjected.vec3[1])])
You are using Homogenious Coordinates to represent the vertices of your model. So the W component must be 1.
When you load your model you are setting W to 0.
verts.append(vec3(float(values[1]), float(values[2]), float(values[3]), 0 ))
By setting W=0 you are creating a Homogenious Vector (a.k.a "point at infinity" or "ideal point") and by setting W=1 you are creating a Homogeneous Point.
Points can be translated but vectors cannot.
https://en.m.wikipedia.org/wiki/Homogeneous_coordinates

Earth&Moon orbit system. My data is wrong

There is my code. I fixed it like this:
# Take 3 digits for significant figures in this code
import numpy as np
from math import *
from astropy.constants import *
import matplotlib.pyplot as plt
import time
start_time = time.time()
"""
G = Gravitational constant
g0 = Standard acceleration of gravity ( 9.8 m/s2)
M_sun = Solar mass
M_earth = Earth mass
R_sun = Solar darius
R_earth = Earth equatorial radius
au = Astronomical unit
Astropy.constants doesn't have any parameter of moon.
So I bring the data from wikipedia(https://en.wikipedia.org/wiki/Moon)
"""
M_moon = 7.342E22
R_moon = 1.737E6
M_earth = M_earth.value
R_earth = R_earth.value
G = G.value
perigee, apogee = 3.626E8, 4.054E8
position_E = np.array([0,0])
position_M = np.array([(perigee+apogee)/2.,0])
position_com = (M_earth*position_E+M_moon*position_M)/(M_earth+M_moon)
rel_pE = position_E - position_com
rel_pM = position_M - position_com
F = G*M_moon*M_earth/(position_M[0]**2)
p_E = {"x":rel_pE[0], "y":rel_pE[1],"v_x":0, "v_y":(float(F*rel_pE[0])/M_earth)**.5}
p_M = {"x":rel_pM[0], "y":rel_pM[1],"v_x":0, "v_y":(float(F*rel_pM[0])/M_moon)**.5}
print(p_E, p_M)
t = range(0,365)
data_E , data_M = [], []
def s(initial_velocity, acceleration, time):
result = initial_velocity*time + 0.5*acceleration*time**2
return result
def v(initial_velocity, acceleration, time):
result = initial_velocity + acceleration*time
return result
dist = float(sqrt((p_E["x"]-p_M['x'])**2 + (p_E["y"]-p_M["y"])**2))
xE=[]
yE=[]
xM=[]
yM=[]
data_E, data_M = [None]*len(t), [None]*len(t)
for i in range(1,366):
data_E[i-1] = p_E
data_M[i-1] = p_M
dist = ((p_E["x"]-p_M["x"])**2 + (p_E["y"]-p_M["y"])**2)**0.5
Fg = G*M_moon*M_earth/(dist**2)
theta_E = np.arctan(p_E["y"]/p_E["x"])
theta_M = theta_E + np.pi #np.arctan(data_M[i-1]["y"]/data_M[i-1]["x"])
Fx_E = Fg*np.cos(theta_E)
Fy_E = Fg*np.sin(theta_E)
Fx_M = Fg*np.cos(theta_M)
Fy_M = Fg*np.sin(theta_M)
a_E = Fg/M_earth
a_M = Fg/M_moon
v_E = (p_E["v_x"]**2+p_E["v_y"]**2)**.5
v_M = (p_M["v_x"]**2+p_M["v_y"]**2)**.5
p_E["v_x"] = v(p_E["v_x"], Fx_E/M_earth, 24*3600)
p_E["v_y"] = v(p_E["v_y"], Fy_E/M_earth, 24*3600)
p_E["x"] += s(p_E['v_x'], Fx_E/M_earth, 24*3600)
p_E["y"] += s(p_E['v_y'], Fy_E/M_earth, 24*3600)
p_M["v_x"] = v(p_M["v_x"], Fx_M/M_moon, 24*3600)
p_M["v_y"] = v(p_M["v_y"], Fy_M/M_moon, 24*3600)
p_M["x"] += s(p_M['v_x'], Fx_M/M_moon, 24*3600)
p_M["y"] += s(p_M['v_y'], Fy_M/M_moon, 24*3600)
for i in range(0,len(t)):
xE += data_E[i]["x"]
yE += data_E[i]["y"]
xM += data_M[i]["x"]
yM += data_M[i]["y"]
print("\n Run time \n --- %d seconds ---" %(time.time()-start_time))
after run this code i tried to print data_E and data_M.
Then I can get data but there is no difference. All of the data is the same.
But when I printed data step by step, it totally different.
I have wrong data problem and increase distance problem. Please help me this problem..
The code exits near line 45, where you are trying to assign p_E by pulling the square root of a negative number on the right hand side (as you've moved the [0] coordinate of the Earth to negative values while shifting Earth and Moon into the coordinate system of their center of mass). In line 45, the value of F*rel_pE[0]/M_earth is negative. So the code never reaches the end of the program using python 2.7.14. That bug needs to be solved before trying to discuss any further aspects.

Numerical issue in scipy.ode.integrate solver

I am using ode solver to solve stiff problem (since odeint function could not able to solve it). But by this way also I have some warnings and my plot get saturate at some point. Here is image What should I do? Here is the list of warnings:
DVODE-- Warning..internal T (=R1) and H (=R2) are
such that in the machine, T + H = T on the next step
(H = step size). solver will continue anyway
In above, R1 = 0.3667661010318D+00 R2 = 0.1426374862242D-16
DVODE-- Warning..internal T (=R1) and H (=R2) are
such that in the machine, T + H = T on the next step
(H = step size). solver will continue anyway
In above, R1 = 0.3667661010318D+00 R2 = 0.1426374862242D-16
DVODE-- Above warning has been issued I1 times.
it will not be issued again for this problem
In above message, I1 = 2
DVODE-- At current T (=R1), MXSTEP (=I1) steps
taken on this call before reaching TOUT
In above message, I1 = 500
In above message, R1 = 0.3667661010318D+00
My code:
import numpy as np
import matplotlib.pyplot as plt
import scipy.integrate as si
def func():
#arguments:::
w = 1./3.
xi = 2.86
phi1 = 1.645
phi2 = 2.* 1.202
gt = 10.**(-60)
Lt = (1.202*gt)/np.pi
Lin = 10.**-5
Lf = 0.49
dt = 0.0001
gin = gt*Lt/Lin
xin = (-np.log((3. - (xi**2)*Lin)/(3. - (xi**2)*Lt)) + np.log(Lin/Lt))/4.0
uin = -(np.log(Lin/Lt))/2.
state0 = [gin,xin,uin]
print state0
def eq(L, state):
g = state[0]
x = state[1]
u = state[2]
N = (-2.*g/(6.*np.pi + 5.*g))*(18./(1. - 2.*L) + 5.*np.log(1.- 2.*L) - phi1 + 6. )
B = (-(2. - N)*L) - ((g/np.pi)* (5.*np.log(1.-2.*L) - phi2 + (5.*N/40.)))
Eqs = np.zeros((3))
gdl = Eqs[0] = ((2.+N)*g)/B
xdl = Eqs[1] = -(2./(3.*(1.+w)))* (1./(1.-(xi**2)*L/3.))*(1./B)
udl = Eqs[2]= 1./B
return Eqs
ode = si.ode(eq)
# BDF method suited to stiff systems of ODEs
ode.set_integrator('vode',nsteps=500,method='bdf')
ode.set_initial_value(state0,Lin)
L = []
G = []
while ode.successful() and ode.t < Lf:
ode.integrate(ode.t + dt)
L.append(ode.t)
G.append(ode.y)
lam = np.vstack(L)
g,x,u = np.vstack(G).T
return g,x,u,lam
r= func()
L = r[3]
g = r[0]
lng = np.log10(g)
x = r[1]
u = r[2]
w = 1./3.
xi = 2.86
O_A = np.zeros(len(L))
q = np.zeros(len(L))
for i in np.arange(len(L)):
O_A[i] = xi**2*L[i]/3.
alpha = 2./ ((3.+3.*w) * (1.- (L[i]*xi**2)/3.) )
q[i] = 1./alpha - 1.
n = np.zeros(len(L)) #eta(n)
b = np.zeros(len(L))
for j in np.arange(len(L)):
n[j] =(-2.*g[j]/(6.*np.pi + 5.*g[j]))*(18./(1. - 2.*L[j]) + 5.*np.log(1.- 2.*L[j]) - 1.645 + 6. )
b[j]= (-(2. - n[j])*L[j]) - ((g[j]/np.pi)* (5.*np.log(1.-2.*L[j]) - 2.* 1.202 + ((5.*n[j])/4.)))
P = np.zeros(len(x))
for k in np.arange(len(x)):
C = (((3. - (xi**2)*L[k])/g[k])**(3./4.)) * (((2.*L[k] + (u[k]*b[k]))*xi**2) + (n[k] * (3.- L[k]*xi**2)) )
P[k] = (np.exp(3.*x[k])) * (np.exp(4.*u[k])) * C
plt.figure()
plt.plot(L,P)
plt.xlabel('Lambda ---->')
plt.ylabel('P ----->')
plt.title('lambda Vs P')
plt.show()

FEniCS: UMFPACK reports that the matrix being solved is singular

I created a divided domain with the stokes-equation in the first subdomain and the mixed-poisson-equation (darcy) in the second subdomain. I work with the UnitSquare and the subdomain 1 should be the interval from 0 to 0,5 and the subdomain 2 from 0,5 to 1.
But now i get the following error:
Solving linear variational problem.
UMFPACK problem related to call to numeric
* Warning: UMFPACK reports that the matrix being solved is singular.
UMFPACK problem related to call to solve
* Warning: UMFPACK reports that the matrix being solved is singular.
assert vmax>=vmin, "empty range, please specify vmin and/or vmax"
Assertion error: empty range, please specify vmin and/or vmax
Can anyone help?
Thanks!
Here is the code:
enter code here
#-*- coding: utf-8 -*-
from dolfin import *
import numpy as np
# Define mesh
mesh = UnitSquare(32,32)
#Subdomain 1
# Gitter übergeben
subdomains = CellFunction("uint", mesh)
# Klasse des Teilgebiets
class Domain_1(SubDomain):
def inside(self, x, on_boundary):
return between(x[0], (0, 0.5)) # Koordinatenangabe des Teilgebiets
# Objekt der Klasse erstellen
sub_domain1 = Domain_1()
sub_domain1.mark(subdomains,0)
# Definition Funktionenräume
U = FunctionSpace(mesh, "CG", 2)
V = FunctionSpace(mesh, "CG", 1)
W = U*V
# Definition Trial- und Testfunktion
(u, p) = TrialFunctions(W)
(v, q) = TestFunctions(W)
# boundary condition
p_in = 1
p_out = 0
noslip = DirichletBC(W.sub(0), (0),
"on_boundary && \
(x[1] <= DOLFIN_EPS | x[1] >= 0.5-DOLFIN_EPS)")
inflow = DirichletBC(W.sub(1), p_in, "x[0] <= 0.0 + DOLFIN_EPS*1000")
outflow = DirichletBC(W.sub(1), p_out, "x[0] >= 0.5 - DOLFIN_EPS*1000")
bcp = [noslip,inflow, outflow]
# Definition f
f = Expression("0")
# Variationsformulierung
a = inner(grad(u), grad(v))*dx + div(v)*p*dx(0) + q*div(u)*dx(0)
L = inner(f,v)*dx(0)
# Lösung berechnen
w = Function(W)
problem = LinearVariationalProblem(a, L, w, bcp)
solver = LinearVariationalSolver(problem)
solver.solve()
(u, p) = w.split()
# Subdomain 2
# Gitter übergeben
subdomains = CellFunction("uint", mesh)
# Klasse des Teilgebiets
class Domain_2(SubDomain):
def inside(self,x,on_boundary):
return between(x[0], (0.5,1.0)) # Koordinatenangabe des Teilgebiets
# Objekt der Klasse erstellen
sub_domain2 = Domain_2()
sub_domain2.mark(subdomains,1)
# Define function spaces and mixed (product) space
BDM = FunctionSpace(mesh, "BDM", 1)
DG = FunctionSpace(mesh, "DG", 0)
CG = FunctionSpace(mesh, "CG", 1)
W = MixedFunctionSpace([BDM, DG, CG])
# Define trial and test functions
(sigma, u, p) = TrialFunctions(W)
(tau, v, q) = TestFunctions(W)
#Define pressure boundary condition
p_in = 1
p_out = 0
noslip = DirichletBC(W.sub(1), (0),
"on_boundary && \
(x[1] <= 0.5 + DOLFIN_EPS | x[1] >= 1.0-DOLFIN_EPS)")
inflow = DirichletBC(W.sub(2), p_in, "x[0] <= 0.5 + DOLFIN_EPS*1000")
outflow = DirichletBC(W.sub(2), p_out, "x[0] >= 1.0 - DOLFIN_EPS*1000")
bcp = [noslip,inflow, outflow]
# Define f
#f = Expression("0")
f = Expression("10*exp(-(pow(x[0] - 0.5, 2) + pow(x[1] - 0.5, 2)) / 0.02)")
# Define variational form
a = (dot(sigma, tau) + div(tau)*u + div(sigma)*v)*dx(1) + inner(p,q)*dx(1) + u*q*dx(1)
L = f*v*dx(1)
# Compute solution
w = Function(W)
problem = LinearVariationalProblem(a, L, w, bcp)
solver = LinearVariationalSolver(problem)
solver.solve()
(sigma, u, p) = w.split()
# plot
plot(u, axes = True, interactive=True, title = "u")
plot(p, axes = True, interactive=True, title = "p")
I forgot the dx(0) in this term. But this was not the problem.
In the first part of the code (Stokes) I tried to write the no slip condition in the following way:
# Randbedingungen
def top_bottom(x, on_boundary):
return x[1] > 1.0 - DOLFIN_EPS or x[1] < DOLFIN_EPS
noslip = Constant((0.0,0.0))
bc0 = DirichletBC(W.sub(0), noslip, top_bottom)
p_in = 1
p_out = 0
inflow = DirichletBC(W.sub(1), p_in, "x[0] <= 0.0 + DOLFIN_EPS*1000")
outflow = DirichletBC(W.sub(1), p_out, "x[0] >= 0.5 - DOLFIN_EPS*1000")
bcp = [bc0, inflow, outflow]
# Definition f
f = Expression("(0.0, 0.0)")
# Variationsformulierung Stokes
a = inner(grad(u), grad(v))*dx(0) + div(v)*p*dx(0) + q*div(u)*dx(0)
L = inner(f,v)*dx(0)
But now I get the following error:
Shape mismatch: line 56, in <module> L = inner(f,v)*dx(0
Can anyone help? Thanks!
I think there are several mistakes here. In the first part of the code I think you are using Taylor-Hood elements to solve Stokes equation. If this us the case, then U should be:
U = VectorFunctionSpace(mesh, "CG", 2)
Also in this part of the code:
a = inner(grad(u), grad(v))*dx + div(v)*p*dx(0) + q*div(u)*dx(0)
L = inner(f,v)*dx(0)
I don't know why you are not using dx(0) for the first term. I encourage you to look at the demos at: http://fenicsproject.org/documentation/dolfin/dev/python/demo/index.html
You might get some more tips.

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