Home / Examples / Fluid Analysis [Bernoulli] / Example 1: Laminar Flow between Parallel Plates

Example 1: Laminar Flow between Parallel Plates

General

The fluid flowing at the constant velocity between the parallel plates is studied in the steady-state analysis.
The flow velocity distribution, the temperature distribution and the flow velocity vectors are solved.
Unless specified in the list below, the default conditions will be applied.

Results will vary depending on Femtet version and the PC environment.

Analysis Space

Item	Settings
Analysis Space	2D
Model Unit	mm

Show Results

Item	Settings
Solver	Fluid Analysis [Bernoulli]
Analysis Type	Steady-state Analysis
Laminar Flow/Turbulent Flow	Select Laminar Flow
Meshing Setup	General Mesh Size: 1 [mm]

Model

The Air (000_Air) is set to a rectangular sheet body. The boundary conditions of inlet and outlet are set on the left edge and the right edge, respectively.

The solid wall is automatically applied to the top and bottom edges where the boundary condition is not set, as the outer boundary condition.

Body Attributes and Materials

Body Number/Type	Body Attribute Name	Material Name
0/Solid	Flow_path	000_Air(*)

* Available from the material DB

Boundary Condition

Boundary Condition Name/Topology	Tab	Boundary Condition Type	Settings
Inlet/Edge	Fluid	Inlet	Force Inflow Flow Velocity Specified 0.1 [m/s]
Outlet/Face	Fluid	Outlet	Natural Outflow

The Reynolds number calculated from this model form, material property, and flow velocity is about 63. It is small enough to analyze the laminar flow.

Generally, the laminar flow transitions to turbulent flow at the Reynolds number in the order of 1000.

Viscosity: μ=1.816e-5 [Pa s]

Density: ρ=1.144 [kg/m3]

Kinematic Viscosity: v=μ/ρ=1.816e-5/1.144=1.587e-5 [m2/s]

Flow Velocity: V=0.1 [m/s]

Distance between Plates: L=0.01 [m]

Reynolds Number: Re = V*L/ν=0.1*0.01/1.587e-5 = 63

Results

The distribution of the flow velocities is shown below.

A graph below is given by selecting [Graph on edge] after right-clicking an edge near the outlet.

The laminar flow is known to show parabolic distribution of flow velocities. From the graph, it can be confirmed that the distribution is parabolic.

The maximum velocity in the center is said to be around 1.5 times the average flow velocity. It also can be confirmed from the graph that the maximum value is about 1.5 times the inflow velocity of 0.1 [m/s].