http://sic.g-eau.fr/ en SPIP - www.spip.net (Sarka-SPIP) https://sic.g-eau.fr/local/cache-vignettes/L32xH32/siteon0-e5814.png?1519033774 http://sic.g-eau.fr/ 32 32 https://sic.g-eau.fr/engelund-hansen-1967,1033 https://sic.g-eau.fr/engelund-hansen-1967,1033 2012-06-21T14:30:37Z text/html en Louis Poirel <p>Engelund-Hansen formula <br class='autobr' /> Transport capacity is calculated as follows : <br class='autobr' /> $$C_eq=0.05\rho_S\fracLU^2Q\frac(JR)^\frac32\sqrtg (\rho_S/\rho-1)^2d$$ <br class='autobr' /> where : $ \rho_S$ is the sediment's density (kg/m3) $ L $ is the stream's width (m) $ U $ is the mean velocity (m/s) $ Q $ is the water discharge (m3/s) $ J $ is the slope (m/m) $ R $ is the hydraulic radius (m) $ g $ is the gravity (m/s2) $ \rho $ is the density of water (kg/m3) $ d $ is the sediment diameter Specifications Law's ID : 561 Number (...)</p> - <a href="https://sic.g-eau.fr/-lois-d-echange-pour-les-algues-en-" rel="directory">Exchange laws for sediment</a> <div class='rss_texte'><h3 class="spip"><a id="engelund-hansen-formula" name="engelund-hansen-formula"></a><a id="a1" name="a1"></a>Engelund-Hansen formula</h3> <p>Transport capacity is calculated as follows :<br class='autobr' /> <p class="spip" style="text-align: center;">$$C_{eq}=0.05\rho_S\frac{LU^2}{Q}\frac{(JR)^{\frac{3}{2}}}{\sqrt{g} (\rho_S/\rho-1)^2d}$$</p> </p> <p>where :</p> <ul class="spip"><li> $ \rho_S$ is the sediment's density (kg/m³)</li><li> $ L $ is the stream's width (m)</li><li> $ U $ is the mean velocity (m/s)</li><li> $ Q $ is the water discharge (m³/s)</li><li> $ J $ is the slope (m/m)</li><li> $ R $ is the hydraulic radius (m)</li><li> $ g $ is the gravity (m/s²)</li><li> $ \rho $ is the density of water (kg/m³)</li><li> $ d $ is the sediment diameter</li></ul> <h3 class="spip"><a id="specifications-1" name="specifications-1"></a><a id="a2" name="a2"></a>Specifications</h3> <ul class="spip"><li> Law's ID : 561</li><li> Number of acting classes : 4</li><li> Number of parameters : 6</li></ul> <p>Acting classes :</p> <ol class="spip"><li> $ C_i $ : transported class modified by the law</li><li> $ C_j $ : fix class modified by the law</li><li> $ C_k $ : transported parameter class ($i=k$ for standard use)</li><li> $ T $ : water temperature</li></ol> <p>Parameters :</p> <ol class="spip"><li> $ d $ : sediment diameter</li><li> $ \rho_S$ : sediment density</li><li> $ p $ : sediment porosity</li><li> $ \alpha$</li><li> $ i_{ech}$ : exchange formula : 1 = Han, 2 = Hazen</li><li> $\beta$</li></ol></div> https://sic.g-eau.fr/sediment-transport https://sic.g-eau.fr/sediment-transport 2012-06-21T14:08:26Z text/html en Louis Poirel <p>Generalities <br class='autobr' /> The calculation of sediment exchanges involves three steps: Calculating an equilibrium concentration $C_eq$ according to a proposed law; Calculating an adaptation time following of Han's formula$t_A=\beta\fracRu*VW$ or Hazen's formula: $t_A=\beta\fracRW$ where $W$ is the fall velocity; Calculation of the exchange term$E=\frac \alpha C_eq-C t_A$ ; <br class='autobr' /> where $\alpha$ and $\beta$ are dimensionless parameters. <br class='autobr' /> The fall rate is calculated according to Zanke's formula: (...)</p> - <a href="https://sic.g-eau.fr/-lois-d-echange-pour-les-algues-en-" rel="directory">Exchange laws for sediment</a> <div class='rss_texte'><h3 class="spip"><a id="engelund-hansen-formula" name="engelund-hansen-formula"></a><a id="a1" name="a1"></a>Generalities</h3> <p>The calculation of sediment exchanges involves three steps:</p> <ul class="spip"><li> Calculating an equilibrium concentration $C_{eq}$ according to a proposed law;</li><li> Calculating an adaptation time following of Han's formula$t_A=\beta\frac{Ru*}{VW}$ or Hazen's formula: $t_A=\beta\frac{R}{W}$ where $W$ is the fall velocity;</li><li> Calculation of the exchange term$E=\frac {\alpha C_{eq}-C }{t_A}$ ;<br class='autobr' /> where $\alpha$ and $\beta$ are dimensionless parameters.</li></ul> <p>The fall rate is calculated according to Zanke's formula:<br class='autobr' /> <p class="spip" style="text-align: center;">$$W=1.1*10\frac{\nu}{d}\left(\sqrt{1+\frac{0.01 g (\rho_S/\rho-1)d^3}{\nu^2}}-1\right)$$</p> <br class='autobr' /> This law is equal to Stokes' law for small diameters, and Newton's law for larger particles.</p></div>