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Closing on wall functions - part 3: a standard wall function

Posted April 23, 2022 at 06:41 by sbaffini (NuTBox)
Updated May 15, 2022 at 04:20 by sbaffini

We make the following assumption for the turbulent viscosity ratio:

\frac{\mu_t}{\mu} = \left\{
        \begin{array}{ll}
            0 & \text{for } y^+ < y_v^+ \\
            \kappa y^+ & \text{for } y^+ \geq y_v^+
        \end{array}
\right.

where \kappa is the von Karman constant and y_v^+ is, for the moment, an unspecified positive parameter. One can then show that the following results:

...
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Closing on wall functions - part 2: the iterative procedure

Posted April 23, 2022 at 06:39 by sbaffini (NuTBox)
Updated May 14, 2022 at 17:30 by sbaffini

The first step in the wall function approach delineated in the first post of this series requires determining \tau_w from

\tau_w = \frac{\left[\left(U_p - U_w\right) \left(\frac{\mu}{y_p}\right) - y_p\sum_{i=0}^{N}\frac{F_U^i}{i+1}\left(\frac{{s_U^i}^+}{{y^+}^{i+2}}\right)\bigg\rvert_{y_p^+} \right]}{\left(\frac{{s_U^{-1}}^+}{y^+}\right)\bigg\rvert_{y_p^+}}

with analogous steps also required for the temperature and scalars. If one has a mean to univocally/externally...
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Closing on wall functions - part 1: Problem statement and general solution

Posted April 23, 2022 at 06:36 by sbaffini (NuTBox)
Updated May 14, 2022 at 17:55 by sbaffini

This is the last series of posts on wall functions, where I summarize previous findings and give them a broader context. I won't provide derivations (hopefully I'll have time to put this in a larger note), but just few statements with the proper scripts to test them.

This all started with the aim to solve the following problem:

\frac{d}{dy}\left[C_p\left(\frac{\mu}{Pr}+\frac{\mu_t}{Pr_t}\right)\frac{dT}{dy}\right]=F_T

with boundary conditions...
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CFD Blog (1): OpenFOAM small bits: How to compile new solver

Posted December 27, 2021 at 12:42 by Ash Kot

Hello Engineers and Scientists,

Preamble:
(If this is your first time then you may like read it, or you can skip it if itís not your first time)

Being involved in CFD engineering and development/programming, I decided to dedicate some of the learning to community by writing through blog towards new budding CFD developers and engineers. So that new people donít have to start from scratch. In this blog series, I shall try to create link to connect my files over...
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CFD Post Expression over time chart (without monitor point)

Posted December 9, 2021 at 06:58 by oakin

So easy solution for time dependent analysis charts.

Quote:
Originally Posted by Badi View Post
well I found it out. Just for everyone whoever finds it.

1. Make the Expression you want. (e.g. volumeInt(vapour.Volume Fraction)@Default Domain)

2. Make a chart and tick the transient box => location: Expression

3. Take the x-axis time and y-axis with the variable from your expression

4. click apply and see your expression over time chart
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