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rotorpy/wind/spatial_winds.py

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+"""
+Here is an example of a static spatial wind field. 
+"""
+import numpy as np
+
+class WindTunnel(object):
+    """
+    This profile is a cylindrical column of air pointing at (0,0,0). Outside of this column the wind is zero. 
+    """
+
+    def __init__(self, mag=1, dir=np.array([1,0,0]), radius=1):
+        """
+        Inputs: 
+            magnitude, a scalar representing the strength of the wind column
+            direction, a vector describing the direction of the wind column
+                e.g., [1,0,0] means the column will be directed in the positive x axis
+            radius, the size of the column (the radius of the cylinder) in meters. 
+            
+        """
+
+        self.mag = mag
+        if np.linalg.norm(dir) > 1: # Check if this is a unit vector. If not, normalize it. 
+            self.dir = dir/np.linalg.norm(dir)
+        else:
+            self.dir = dir
+        self.radius = radius
+
+    def update(self, t, position):
+        """
+        Given the present time and position of the vehicle in the world frame, return the
+        current wind speed on all three axes. 
+        """
+
+        # We can get the perpendicular distance of the vector xi+yj+zk from the line self.dir 
+        # using the cross product. This assumes that ||self.dir|| = 1 and that the column
+        # passes through the origin (0,0,0). 
+
+        if np.linalg.norm(np.cross(position, self.dir)) <= self.radius:
+            # If this condition passes, we're within the column. 
+            wind = self.mag*self.dir
+        else:
+            wind = np.array([0,0,0])
+
+        return wind