This simulation shows 2 dimensional vector fields, more specifically the xy cross section of a 3 dimensional vector field constant in z direction (as with a cylinder of infinite extension).
Shown are flow fields characterized by local velocity components a_x in the x direction and a_y in the y direction. Arrows with uniform length display the direction of the resulting flow vector. The size of the vector is indicated qualitatively by color gradation.
When opening the simulation, a field with two vortices is demonstrated. Two white text fields show the formulas of its vector components. A blue text field shows the divergence of the field, a brown field the 3D coordinates of its rotation vector.
In a combobox one can choose among many predefined fields. The type of field and the components of its vectors are stated. The second case is empty for your own data insertions. Alternatively you can edit data of predefined cases in the a_x and a_y text fields (do not forget to press the Enter button after changes!)
Changing to another predefined function erases old data. If you want to preserve the result of your own changes, fabricate a picture, (most simply by pressing the Print button of your keyboard to transfer the window data into the temporary store; then paste them into a suitable document. A more comfortable way is to use a screenshot reader).
A red test object lies in the vector field that will follow the flow vector both in direction and value once the start button is activated. It jumps back to its initial position when it crosses the limits of the field. Step causes one step of movement.
You can draw the object with the mouse, and test the field at every position that way. This gives an impression of direction and value within the whole field.
You can turn off the vector arrows with an option switch and try to understand the field just from the movement of the test body.
The zoom slider changes the scale of coordinates. As the number of arrows shown is constant, this helps to recognize details. The default case with two vortices is a good example.
The arrow length slider changes the length of arrows, init resets all parameters , reset_point resets the test object to the default position.