What type of flow is characterized by irregular curves in the path lines of flow that continually cross each other?

The type of flow characterized by irregular curves in the path lines that continually cross each other is indeed turbulent flow. In turbulent flow, the movement of fluid particles is chaotic and mixed, leading to the formation of eddies and vortices. This randomness manifests as fluctuating velocities and directions, which results in the intertwining of different flow threads, creating the irregular paths described.

In contrast, laminated flow (often referred to as laminar flow) is characterized by smooth and orderly layers of fluid that slide past one another without mixing, exhibiting parallel streamlines. Viscous flow refers to the influence of viscosity on the flow behavior but does not inherently define the chaotic interaction of particles observed in turbulent dynamics. Steady flow describes a condition where the velocity of fluid particles at any given point does not change over time, which is not a characteristic associated with the crossing paths and irregular patterns found in turbulent flow.