# Can two streamlines in a fluid be tangential to each other not crossing each other?

A streamline cannot cross other one in steady state of a fluid but can they be tangent to each other ?

What I mean is consider fluid in steady state. if let us say particle A has its own path in fluid and at point B it has velocity x. But let us say another particle C has its own path and has to cross ppoint B it must also have same velocity and hence the two streamlines are tangent at B. Is this possible otlr is it only valid if particle A and C both have the exact same trajectory fro the beginning ?

• In steady flow, the streamlines can't be tangent either. Mar 23, 2017 at 11:31
• To elaborate Chester Miller's comment, in an unsteady flow streamlines change from one instant to another. Therefore it is possible that at different instants of time, two different streamlines pass through the same point in space. However even in unsteady flow, at a given instant in time, only one streamline can pass through a given point in space.
– Deep
Mar 24, 2017 at 5:26