I understand that there are vortices formed on the delta wing for moderate angles and low speeds. I observed recently 2 asymmetric vortices forming on a small delta wing model for a moderate angle and a low speed. But, why would there be asymmetriic flow over a delta wing? If the flow is approaching the wing symmetrically and the wing itself is symmetric about the same plane, the flow should be symmetric, right? And ofcourse, i'm talking about the plane at right angles to the wing and containing the root chord in it.