[Yoshiki]

Thanks, Alczem and Severus!

Originally Posted by Yoshiki

Also, when pFinal and UFinal were set to 1e-2 and 1e-3 respectively, the analysis converged in 114 iterations, and the results were almost the same as those obtained from a 1000-iteration analysis

without setting

residualControl
    {
        p               1e-2;
        U               1e-3;
     }

At that time I had mistakenly set final residual and residualControl, and it was that the convergence was faster when I set the residualControl as above. Sorry for the confusion.

solvers
{
    p
    {
        solver          GAMG;
        smoother        GaussSeidel;
        tolerance       1e-7;
        relTol          0.01;
    }

    pFinal
    {
        $p;
        tolerance       1e-06;
        relTol          0;
    }


    Phi
    {
        $p;
    }

    U
    {
        solver          smoothSolver;
        smoother        GaussSeidel;
        tolerance       1e-8;
        relTol          0.1;
        nSweeps         1;
    }

    k
    {
        solver          smoothSolver;
        smoother        GaussSeidel;
        tolerance       1e-8;
        relTol          0.1;
        nSweeps         1;
    }

    omega
    {
        solver          smoothSolver;
        smoother        GaussSeidel;
        tolerance       1e-8;
        relTol          0.1;
        nSweeps         1;
    }
}

SIMPLE
{
    nNonOrthogonalCorrectors 0;
    consistent yes;
    residualControl
    {
        p               1e-2;
        U               1e-3;
    }
}

Switching to the topic of flow velocity, the centreline velocity remained nearly unchanged: 0.419207 m/s at the inlet cross-section, 0.419172 m/s at the central cross-section along the length (z = 0.025), and 0.419164 m/s at the outlet cross-section.

Additionally, the velocity at the first cell center from the wall was 0.00255349 m/s at the inlet cross-section and 0.00251653 m/s at the central cross-section along the length.Switching to the topic of flow velocity, the centreline velocity remained nearly unchanged: 0.419207 m/s at the inlet cross-section, 0.419172 m/s at the central cross-section along the length (z = 0.025), and 0.419164 m/s at the outlet cross-section.

Additionally, the velocity at the first cell center from the wall was 0.00255349 m/s at the inlet cross-section, 0.00251653 m/s at the central cross-section along the length, and 0.003844769 m/s at the outlet cross-section, where it was noticeably higher.

Additionally, the wall shear stress at the inlet varies depending on the location and is lower than the theoretical value. This also occurs when a uniform flow is introduced into a straight circular pipe with a 0.4 m development section.

I am considering using ParaView's features to investigate how wall shear stress is calculated based on the gradient.