Another choice of pressure and density with the same velocity vector above is one where the pressure and density fall to zero at the origin and are highest in the central loop at z = 0, x + y = r : ρ ρ ( x , y , z ) = 20 B ( x 2 + y 2 ) ( r 2 + x 2 + y 2 + z 2 ) 3 p ( x , y , z ) = − − A 2 B ( r 2 + x 2 + y 2 + z 2 ) 4 + − − 4 A 2 B ( x 2 + y 2 ) ( r 2 + x 2 + y 2 + z 2 ) 5 .