## What causes no-slip condition?

It has been established through experimental observations that the relative velocity between the solid surface and the adjacent fluid particles is zero whenever a viscous fluid flows over a solid surface. This is known as no-slip condition.

### What is a no slip wall?

no-slip means the velocity at the wall is zero (this is used for viscous flow) and slip condition will not have zero velocity at the wall ( you need to give shear information).

#### What is free slip boundary condition?

in a simple language you can say that, the free slip boundary condition is required when you do not want your computational boundary to influence your flow. At slip boundary condition the shear stress is taken as zero that means there is no existence of boundary layer formation at that plane.

**When is a slip boundary condition used?**

The slip wall condition is for cases where viscous effects at the wall are negligible and/or your mesh size is much bigger than the boundary layer thickness (so you’re not capturing the boundary layer effects anyway). The slip boundary is also the proper boundary condition for symmetry surfaces.

**What is Navier slip condition?**

The Navier’s slip boundary condition was first proposed by Navier in [1] which states that the component of fluid velocity tangent to the surface should be proportional to the rate of strain at the surface. It can no longer be assumed that the macroscopic properties of the fluid (density, viscosity, etc.)

## What is slip length?

Fluid flow in confined geometries can be significantly affected by slip at the liquid/solid interface. The measure of slip is the so-called slip length, which is defined as an extrapolated distance relative to the wall where the tangential velocity component vanishes (see picture below).

### What type of boundary condition is the no-slip condition?

In fluid dynamics, the no-slip condition for viscous fluids assumes that at a solid boundary, the fluid will have zero velocity relative to the boundary. The fluid velocity at all fluid–solid boundaries is equal to that of the solid boundary.

#### What is the no-slip velocity boundary condition for walls?

For the flow velocity, there are two main types of boundary conditions: no-slip and slip boundary conditions (see Fig. 9.10). In no-slip boundary conditions, the speed of the fluid at the wall is supposed to be zero, whereas in slip boundary conditions there is relative movement between the wall and the fluid.

**What is the no slip condition that all fluids satisfy?**

**How is slip length calculated?**

In such techniques, the velocity profile of the liquid can be measured with high accuracy, and the slip length can be extracted from the equation [24] b=vs/∂vs/∂z, where vs and ∂vs/∂z are the velocity and the shear rate close to the surface.