I want to know how to determine the dimensionless numbers such as Reynolds and Nusselt numbers for my combustion modeling.
Its a CH4/O2 mixture, diameter of tube is 6mm, length of 60mm.
Also, how can it be determined in CFD fluent.
Dear Evans
I do agree with Kourosh Vaferi and Alexandru-Ionel Constantin
Knowing velocity, hydraulic diameter and the fluid properties, you can calculate Re number.
Hydraulic diameter is defined as:
D=4A/P
Hi!
In order to calculate Reynolds number you need to know the velocity, hydraulic diameter and the kinematic viscosity, https://www.engineeringtoolbox.com/reynolds-number-d_237.html .
For Nusselt number you need the Convection Heat Transfer Coefficient , Characteristic Length and Thermal Conductivity of the Fluid, http://www.meracalculator.com/physics/fluid-mechanics/nusselt-number.php
Dear Evans
Re=ρuL/μ
https://en.wikipedia.org/wiki/Reynolds_number
Nu = hL/k
https://en.wikipedia.org/wiki/Nusselt_number
Dear Evans
I do agree with Kourosh Vaferi and Alexandru-Ionel Constantin
Knowing velocity, hydraulic diameter and the fluid properties, you can calculate Re number.
Hydraulic diameter is defined as:
D=4A/P
Dear Quaye,
You can calculate the dynamic viscosity if you know the mole fractions of the mixture.
Also, you need to select the mentioned gases from Fluent's database. Again, you need to specify the mole fractions if you define more than one fluid.
For gas mixture you may calculate the dynamic viscosity and the velocity of the gas mixture and for small pipe length (60mm) You may take the characteristic length is 60mm or the hydraulic diameter(6mm), depends on the nature of gas mixture and the required flow Laminar or Turbulent.Also you may do the above calculations for Nusselt Number.
For the Reynolds you need to define three parameters
velocity,
kinematic viscosity,
hydraulic diameter ,
Dear Evans
take a look at these pages
https://en.wikipedia.org/wiki/Reynolds_number
https://en.wikipedia.org/wiki/Nusselt_number
The Reynolds number (Re) of a flowing fluid is calculated by multiplying the fluid velocity by the internal pipe diameter (to obtain the inertia force of the fluid) and then dividing the result by the kinematic viscosity (viscous force per unit length).
https://www.pipeflow.com/pipe-pressure-drop-calculations
- Badges
- Science topic