Hello everyone,
I am new to this programm and want to simulate the first part of a streamed circular duct. It serves as an hydrodynamical entry length to develop the velocity flow profile. In the second part (not part of this simulation) the duct is affected by a heat flux to develop the thermal flow profile separately.
Therefore I chose the "laminar flow" physics and used "normal inflow velocity" as a inlet boundary condition. Using "pressure, no viscous stress" as outlet boundary condition COMSOL archieves a solution.
But I want to consider the first part of the duct continued in the earlier explained second part.
So I chose "laminar outflow" as outlet boundary condition with an average velocity=[inflow velocity] (due to unchanged temperature/density) and an exit length=[length of the second part of the circular duct]. Now COMSOL gives the error:
"Failed to find a solution.
Maximum number of Newton iterations reached.
Returned solution is not converged."
Both parts are calculated long enough to serve as an entry/exit length. Re is always <2300.
Please give me a hint about what I did wrong!
Sincerely, Fabian
EDIT: I found out that the max. velocity (2*entry velocity) does not get reached, although the entry length is much longer than 0,056*(Re=2300)*d ?!
I am new to this programm and want to simulate the first part of a streamed circular duct. It serves as an hydrodynamical entry length to develop the velocity flow profile. In the second part (not part of this simulation) the duct is affected by a heat flux to develop the thermal flow profile separately.
Therefore I chose the "laminar flow" physics and used "normal inflow velocity" as a inlet boundary condition. Using "pressure, no viscous stress" as outlet boundary condition COMSOL archieves a solution.
But I want to consider the first part of the duct continued in the earlier explained second part.
So I chose "laminar outflow" as outlet boundary condition with an average velocity=[inflow velocity] (due to unchanged temperature/density) and an exit length=[length of the second part of the circular duct]. Now COMSOL gives the error:
"Failed to find a solution.
Maximum number of Newton iterations reached.
Returned solution is not converged."
Both parts are calculated long enough to serve as an entry/exit length. Re is always <2300.
Please give me a hint about what I did wrong!
Sincerely, Fabian
EDIT: I found out that the max. velocity (2*entry velocity) does not get reached, although the entry length is much longer than 0,056*(Re=2300)*d ?!