Question

Which of these is correct about the first internal node of a k-ε model?

(a) k-equation is not solved

(b) ε-equation is not solved

(c) Both k and ε-equations are not solved

(d) Both k and ε-equations are solved simultaneously

The question was asked by my school teacher while I was bunking the class.

This interesting question is from Turbulence Modelling topic in chapter Turbulence Modelling of Computational Fluid Dynamics

Answer 1

The correct answer is:

(d) Both k and ε-equations are solved simultaneously

Explanation:

In the context of the k-ε turbulence model, both the turbulent kinetic energy equation (k-equation) and the turbulent dissipation rate equation (ε-equation) are solved simultaneously at all points in the flow domain, including the first internal node.

• The k-equation represents the turbulent kinetic energy, which describes the energy in the turbulent fluctuations.
• The ε-equation describes the rate of dissipation of that turbulent energy.

These equations are coupled, meaning that they interact and need to be solved together. The model uses both variables to close the system of equations that describe turbulence. The first internal node in the flow domain will use boundary conditions (such as specified at the inlet or outlet) and then solve both equations simultaneously to provide values for the turbulence quantities at that node.

Thus, at the first internal node (and at all interior nodes), both the k and ε equations are solved together to calculate the turbulence quantities.

Correct Answer: (d) Both k and ε-equations are solved simultaneously