x = np.arange(-10, 10.01, 0.01) + 8
y = np.arange(-10, 10.01, 0.01)

X, Y = np.meshgrid(x, y)

r = np.sqrt(X**2 + Y**2)
theta = np.arctan2(Y, X - 8)
v0 = 233
R = 8
v = v0 * np.sin(theta) * (R / r - 1)

fig, ax = plt.subplots()
ax.set_box_aspect(1)

cs = ax.contour(
    x - 8,
    y,
    v,
    levels=np.arange(-150, 160, 10),
    linewidths=1,
    cmap="coolwarm", # coolwarm
    linestyles="solid",
)
ax.clabel(cs, cs.levels, inline=True, fontsize=8, inline_spacing=10)

plt.colorbar(cs)
plt.show()