 steadi motion conduct fluid pipe transvers magnet field steadi motion conduct fluid pipe transvers magnet field paper studi steadi motion electr conduct viscou fluid channel presenc impos transvers magnet field wall conduct current equat determin veloc profil induc current field deriv solv exactli case rectangular channel impos field strong veloc profil degener core uniform flow surround boundari layer wall layer wall parallel impos field novel charact analog degener solut channel symmetr shape develop predict pressur gradient volum flow field strength final compar experiment squar circular pipe 