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Flow type for air

Calculates whether the airflow is laminar or turbulent in the current duct.

Circular duct

Input Result
Flow q=
Duct diameter d=
Kinematic viscosity ν= *10-6m2/s
Velocity v=
Reynolds number
Flow type

Rectangular duct

Input Result
Flow q=
Duct height a=
Duct width b=
Kinematic viscosity ν= *10-6m2/s
Hastighet v=
Reynolds number
Flow type


Turbulent flow

Turbulent flows are random in the withered that it is impossible to determine which suddenly a flow thing to have in a wise location at a certain time, however, it is possible to describe it statistically. The higher Reynolds number, the more sensitive is the flow of disturbances.

In turbulent flow creates eddies which converts kinetic energy into heat energy, which means that heat losses in a turbulent flow will be higher than in a laminar.

Laminar flow

Laminar flow is linear, which means that they calculate the difference from the turbulent. Laminar flows give rise to lower heat losses and friction than turbulent flow.


The airflow in the current channel.

Duct diameter

The actual diameter of the duct.


The Reynolds number is a dimensionless quantity used in fluid mechanics to calculate on flowing media flow laminar or turbulent. At a Reynolds number of less than 2100, the flow is laminar, while if it exceeds 4000 so the flow is turbulent and in between is a mix between the two. Reynolds number can be seen as the ratio of inertial forces and friction forces, where tubulent flow is dominated by inertial forces.

Kinematic viscosity

Specifies how quickly a liquid spreads relative to its mass if it is poured out on a flat surface.

Hydraulic diameter

Are the rectangular channel and converted to a circular that gives the same friction pressure loss.


Reynolds number: Reynolds number
Flow: Flow
Hydraulic diameter: Hydraulic diameter