Two-dimensional unsteady incompressible flows in which the potential vorticity (PV) plays a key role are examined in this study. through the development of the evolution equation for the PV gradient. For the case where the PV is conserved. precise statements concerning topology-conservation are presented. https://www.bekindtopets.com/hot-choice-Dinner-Lady-Blueberry-Tart-TFN-30mL-Salt-Nicotine-Vape-Juice-best-save/