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Commit 5ee76728 authored by David Dorchies's avatar David Dorchies
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doc(macrorugo): update for new values of Cd0, r and fF(F)

Refs jalhyd#283
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......@@ -6,5 +6,14 @@
"latex",
"plaintext",
"markdown"
],
"cSpell.words": [
"Cassan",
"DICHO",
"MACRORUGO",
"fdescribe",
"jalhyd",
"nghyd",
"prms"
]
}
\ No newline at end of file
docs/en/calculators/pam/cassan2016_flow_chart_design_method.png

102 KiB

......@@ -4,6 +4,10 @@ The calculation of the flow rate of a rock-ramp pass corresponds to the implemen
## General calculation principle
![Organigramme de la méthode de calcul](cassan2016_flow_chart_design_method.png)
*After Cassan et al., 2016[^1]*
There are three possibilities:
- the submerged case when \(h \ge 1.1 \times k\)
......@@ -106,19 +110,23 @@ $$\alpha = 1 - (a_y / a_x \times C)$$
## Formulas used
### Throughput speed *V*
### Bulk velocity *V*
$$V = \frac{Q}{B \times h}$$
### Average speed between blocks *V<sub>g</sub>*
From Eq. 1 Cassan et al (2016)[^1] and Eq. 1 Cassan et al (2014)[^2]:
$$V_g = \frac{V}{1 - \sqrt{(a_x/a_y)C}}$$
<div style="position: relative"><a id="coefficient-de-trainee-dun-bloc-cd0" style="position: absolute; top: -60px;"></a></div>
### Drag coefficient of a single block *C<sub>d0</sub>*
\(C_{d0}\) is the drag coefficient of a block considering a single block
infinitely high with \(F << 1\) (Cassan et al, 2016[^1]).
infinitely high with \(F << 1\) (Cassan et al, 2014[^2]). The coefficient has been readjusted in Cassiopée version 4.14.0 from the coefficients originally proposed in Cassan et al, 2014[^2], Table 2.
It is now 1.1 for a circular block and 2.6 for a flat-faced block.
### Block shape coefficient *σ*
......@@ -126,11 +134,15 @@ Cassan et al. (2014)[^2], et Cassan et al. (2016)[^1] define \(\sigma\) as the r
block area in the \(x,y\) plane and \(D^2\).
For the cylindrical form of the blocks, \(\sigma\) is equal to \(\pi / 4\) and for a square block, \(\sigma = 1\).
The formula used in Cassiopée has been revised to better correspond to the experimental measurements and to take into account the intermediate block shapes between circular and square.:
### Ratio between the average speed downstream of a block and the maximum speed *r*
$$ \sigma = 0.4 C_{d0} + 0.7 $$
Cassan et al. (2014) [^2], Table 2 gives experimental measurements of this ratio for cylindrical blocks (\(r=1.2\)), rounded faces (\(r=1.2)\) and flat faces (\(r=1.5\)).
We now have \(\sigma = 1.1\) for a circular block and \(\sigma = 1.5\) for a square block.
The formula used in Cassiopeia allows to take into account shapes of intermediate blocks between circular and square shapes from the values of \(C_{d0} = 1.1\) for cylindrical blocks and \(C_{d0} = 2.6\) for blocks with flat faces:
$$ r = (C_{d0} *0.4 + 1.121) / 1.5 $$
We now have \(r = 1.1\) for circular blocks and \(r = 1.35\) for flat-faced blocks.
### Froude *F*
......@@ -142,11 +154,29 @@ If \(F < 1.3\) (Eq. 5, Cassan et al., 2016)
$$f_F(F) = \mathrm{min} \left( \frac{\sigma}{1- (F^2 / 4)}, \frac{1}{F^{\frac{2}{3}}} \right)^2$$
else
else (The distinction is only numerical because \(1- (F^2 / 4)\) is not defined for \(F > 2\))
$$f_F(F) = F^{\frac{-4}{3}}$$
(The distinction is only numerical because \(1- (F^2 / 4)\) is not defined for \(F > 2\))
### Maximum speed *u<sub>max</sub>*
According to equation 19 of Cassan et al, 2014[^2] :
$$ f_F(F) = \left( \dfrac{U_d}{V_g} \right)^2 $$
And equation 4:
$$ \frac{u_{max}}{V_g} = r \dfrac{u_d}{V_g} $$
It is deduced that :
$$ u_{max} = V_g r \sqrt{f_F(F)} $$
### Drag coefficient correction function linked to relative depth *f<sub>h\*</sub>(h<sub>\*</sub>)*
The equation used in Cassiopeia differs slightly from Equation 20 of Cassan et al. 2014 [^2] and Equation 6 of Cassan et al. 2016 [^1]. Indeed, recent experiments have shown a better correlation with the following formula :
$$ f_{h_*}(h_*) = \min \left((1 + 1 / h_*^2), 3 \right) $$
### Coefficient of friction of the bed *C<inf>f</inf>*
......
......@@ -122,9 +122,9 @@ $$V_g = \frac{V}{1 - \sqrt{(a_x/a_y)C}}$$
### Coefficient de trainée d'un bloc *C<sub>d0</sub>*
\(C_{d0}\) est le coefficient de trainée d'un bloc de hauteur infinie pour un Froude \(F << 1\) (Cassan et al, 2016[^1]).
\(C_{d0}\) est le coefficient de trainée d'un bloc de hauteur infinie pour un Froude \(F << 1\) (Cassan et al, 2014[^2]). Le coefficient a été réajusté dans la version 4.14.0 de Cassiopée par rapport aux coefficients initialement proposés dans Cassan et al, 2014[^2], Table 2.
Il vaut 1 pour un plot circulaire et 2 pour un plot carré.
Il vaut désormais 1.1 pour un bloc circulaire et 2.6 pour un plot à face plane.
### Coefficient de forme de bloc *σ*
......@@ -135,11 +135,9 @@ On a donc \(\sigma = \pi / 4\) pour un bloc circulaire et \(\sigma = 1\) pour un
Cassan et al. (2014)[^2], Table 2 donne des mesures expérimentales de ce ratio pour les blocs cylindriques (\(r=1.2\)), aux faces arrondies (\(r=1.2)\) et aux faces planes (\(r=1.5\)).
La formule utilisée dans Cassiopée a été remaniée pour mieux correspondre aux mesures expérimentales et permettre une prise en compte de formes de plots intermédiaires entre les formes circulaire et carré&nbsp;:
La formule utilisée dans Cassiopée permet une prise en compte de formes de plots intermédiaires entre les formes circulaire et carré à partir des valeurs de \(C_{d0} = 1.1\) pour les blocs cylindriques et \(C_{d0} = 2.6\) pour les blocs à faces planes&nbsp;:
$$ r = 0.4 C_{d0} + 0.7 $$
On a désormais \(r = 1.1\) pour un plot circulaire et \(r = 1.5\) pour un plot carré.
$$ r = (C_{d0} *0.4 + 1.121) / 1.5 $$
### Froude *F*
......@@ -149,7 +147,7 @@ $$F = \frac{V_g}{\sqrt{gh}}$$
Si \(F < 1.3\) (Eq. 19, Cassan et al., 2014[^2])
$$f_F(F) = \min \left( \frac{r}{1- F^2 / 4}, \frac{1}{F^{\frac{2}{3}}} \right)^2$$
$$f_F(F) = \min \left( \frac{1}{1- F^2 / 4}, \frac{1}{F^{\frac{2}{3}}} \right)^2$$
sinon (distinction numérique car \(\frac{r}{1- (F^2 / 4)}\) est non défini pour \(F > 2\))
......@@ -173,7 +171,7 @@ $$ u_{max} = V_g r \sqrt{f_F(F)} $$
L'équation utilisée dans Cassiopée diffère légèrement de l'équation 20 de Cassan et al. 2014[^2] et l'équation 6 de Cassan et al. 2016[^1]. En effet, les récentes expériences ont montré une meilleure corrélation avec la formule suivante :
$$ f_{h_*}(h_*) = (1 + 1 / h_*^2) $$
$$ f_{h_*}(h_*) = \min \left((1 + 1 / h_*^2), 3 \right) $$
### Coefficient de friction du lit *C<inf>f</inf>*
......
......@@ -4,7 +4,7 @@
* 1) Reads Message enum in jalhyd, and for every message code in it, checks
* that there is a translation in each nghyd's locale/*.json file (ie. for
* every language)
*
*
* 2) For every nghyd calculator, checks that the translated keys are the same
* in all language files
*/
......@@ -35,7 +35,7 @@ jm = jm.replace(/[ \t]+/g, "");
// remove line breaks
jm = jm.replace(/\n/g, "");
// split on ";"
// split on ","
const messages = jm.split(",");
// remove import on 1st line (wtf) @clodo
......
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