I am getting a negative value of Velocity in my Flow Simulation analysis. It is not much, something like - 0.5 m/s

This made me puzzled: How can a velocity of a wind have a negative value???

I know that pressure can have a negative and positive value. Positive value of wind will act like a compressional force towards the object. And negative value of pressure will act like a suction force.

But velocity can only take positive value. How can a velocity take a negative value?

Did I just miss some of the physics classes, or is this just Flow Simulation error?

Thank you for the replies.

I think you're mixing up the terms velocity and speed. Velocity, as Billy indicates above, is a vector quantity and therefore can be negative or positive. Speed is a scalar quantity and because of the way it's defined, is always greater than or equal to zero, since speed is defined as the magnitude of the velocity, that is, the square root of the sum of the squares of each velocity component in a Cartesian coordinate system.