Interior flow and erosion

Storyboard

Internal flow occurs through the capillaries formed between the soil particles. Whenever these capillaries have dimensions greater than those of the small clay plates, there is a risk that these clay particles may be carried away by this flow. If this happens, the soil could lose some of its clay content, which would impact its mechanical properties, stability, and support for organic life.

>Model

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Current on Porosity

Image

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Flow after Hagen-Poiseuille equation

Quote

The profile of the speed on a cylinder radio ($v$) in the radius of position in a tube ($r$) allows us to calculate the volume flow ($J_V$) in a tube by integrating over the entire surface, which leads us to the well-known Hagen-Poiseuille law.



The result is an equation that depends on ERROR:5417,0 raised to the fourth power. However, it is crucial to note that this flow profile only holds true in the case of laminar flow.

Thus, from the viscosity ($\eta$), it follows that the volume flow ($J_V$) before ERROR:5430.1 and ERROR:6673.1, the expression:

$ J_V =-\displaystyle\frac{ \pi R ^4}{8 \eta }\displaystyle\frac{ \Delta p }{ \Delta L }$

The original papers that gave rise to this law with a combined name were:

"Ueber die Gesetze, welche des der Strom des Wassers in röhrenförmigen Gefässen bestimmen" (On the laws governing the flow of water in cylindrical vessels), Gotthilf Hagen, Annalen der Physik und Chemie 46:423442 (1839).

"Recherches expérimentales sur le mouvement des liquides dans les tubes de très-petits diamètres" (Experimental research on the movement of liquids in tubes of very small diameters), Jean-Louis-Marie Poiseuille, Comptes Rendus de l'Académie des Sciences 9:433544 (1840).

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Forces on Plates

Exercise

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Interior flow and erosion

Storyboard

Internal flow occurs through the capillaries formed between the soil particles. Whenever these capillaries have dimensions greater than those of the small clay plates, there is a risk that these clay particles may be carried away by this flow. If this happens, the soil could lose some of its clay content, which would impact its mechanical properties, stability, and support for organic life.

Variables

Symbol
Text
Variable
Value
Units
Calculate
MKS Value
MKS Units
$\bar{v}$
v_m
Average speed
m/s
$h$
h
Column height
m
$r$
r
Cylinder radial position
m
$\rho$
rho
Density
kg/m^3
$e$
e
Energy density
J/m^3
$w_c$
w_c
Height of a clay plate
m
$h_1$
h_1
Height or depth 1
m
$h_2$
h_2
Height or depth 2
m
$l_c$
l_c
Length and width of a clay plate
m
$m_c$
m_c
Mass of a clay plate
kg
$v_{max}$
v_max
Maximum flow rate
m/s
$v_1$
v_1
Mean Speed of Fluid in Point 1
m/s
$v_2$
v_2
Mean Speed of Fluid in Point 2
m/s
$dp$
dp
Pressure Difference Lifting the Clay Plate
Pa
$p_1$
p_1
Pressure in column 1
Pa
$p_2$
p_2
Pressure in column 2
Pa
$s_c$
s_c
Section clay plate
m^2
$\rho_s$
rho_s
Solid Density
kg/m^3
$\Delta v$
Dv
Speed difference between surfaces
m/s
$v$
v
Speed on a cylinder radio
m/s
$\Delta L$
DL
Tube length
m
$R$
R
Tube radius
m
$\Delta p$
Dp
Variación de la Presión
Pa
$\eta$
eta
Viscosity
Pa s
$p$
p
Water column pressure
Pa

Calculations


First, select the equation:   to ,  then, select the variable:   to 

Symbol
Equation
Solved
Translated

Calculations

Symbol
Equation
Solved
Translated

 Variable   Given   Calculate   Target :   Equation   To be used



Equations

Another useful equation is the one corresponding to the conservation of energy, which is applicable in cases where viscosity, a process that leads to energy loss, can be neglected. If we consider the classic energy equation $E$, which takes into account kinetic energy, gravitational potential energy, and an external force displacing the liquid over a distance $\Delta z$, it can be expressed as:

$E=\displaystyle\frac{m}{2}v^2+mgh+F\Delta x$



If we consider the energy within a volume $\Delta x\Delta y\Delta z$, we can replace the mass with:

$m=\rho \Delta x\Delta y\Delta z$



And since pressure is given by:

$F=p \Delta S =p \Delta y\Delta z$



We obtain the equation for energy density:

equation

When a the pressure difference ($\Delta p_s$) acts on a section with an area of $\pi R^2$, with the tube radius ($R$) as the curvature radio ($r$), it generates a force represented by:

$\pi r^2 \Delta p$



This force drives the liquid against viscous resistance, given by:

equation=3623

By equating these two forces, we obtain:

$\pi r^2 \Delta p = \eta 2\pi r \Delta L \displaystyle\frac{dv}{dr}$



Which leads to the equation:

$\displaystyle\frac{dv}{dr} = \displaystyle\frac{1}{2\eta}\displaystyle\frac{\Delta p}{\Delta L} r$



If we integrate this equation from a position defined by the curvature radio ($r$) to the edge where the tube radius ($R$) (taking into account that the velocity at the edge is zero), we can obtain the speed on a cylinder radio ($v$) as a function of the curvature radio ($r$):

equation

Where:

equation=3628

is the maximum flow rate ($v_{max}$) at the center of the flow.

If we assume that the energy density ($e$) is conserved, we can state that for a cell where the average velocity is the speed on a cylinder radio ($v$), the density is the density ($\rho$), the pressure is the water column pressure ($p$), the height is the column height ($h$), and the gravitational acceleration is the gravitational Acceleration ($g$), the following holds:

equation=3159

At point 1, this equation will be equal to the same equation at point 2:

$e(v_1,p_1,h_1)=e(v_2,p_2,h_2)$



where the mean Speed of Fluid in Point 1 ($v_1$), the height or depth 1 ($h_1$), and the pressure in column 1 ($p_1$) represent the velocity, height, and pressure at point 1, respectively, and the mean Speed of Fluid in Point 2 ($v_2$), the height or depth 2 ($h_2$), and the pressure in column 2 ($p_2$) represent the velocity, height, and pressure at point 2, respectively. Therefore, we have:

equation

In the case where there is no hystrostatic pressure, Bernoulli's law for the density ($\rho$), the pressure in column 1 ($p_1$), the pressure in column 2 ($p_2$), the mean Speed of Fluid in Point 1 ($v_1$) and the mean Speed of Fluid in Point 2 ($v_2$)

equation=15495

can be rewritten with the variación de la Presión ($\Delta p$)

equation=4252

and keeping in mind that

$v_2^2 - v_1^2 = \displaystyle\frac{1}{2}(v_2-v_1)(v_1+v_2)$



with

equation=15501

and

equation=15502

you have to

equation


Examples

Since a fluid or gas is a continuum, the concept of energy can no longer be associated with a specific mass. However, it is possible to consider the energy contained in a volume of the continuum, and by dividing it by the volume itself, we obtain the energy density ($e$). Therefore, with the density ($\rho$), the speed on a cylinder radio ($v$), the column height ($h$), the gravitational Acceleration ($g$), and the water column pressure ($p$), we have:

kyon

which corresponds to the Bernoulli equation.

With the mean Speed of Fluid in Point 1 ($v_1$), the height or depth 1 ($h_1$), and the pressure in column 1 ($p_1$) representing the velocity, height, and pressure at point 1, respectively, and the mean Speed of Fluid in Point 2 ($v_2$), the height or depth 2 ($h_2$), and the pressure in column 2 ($p_2$) representing the velocity, height, and pressure at point 2, respectively, we have:

kyon

The variación de la Presión ($\Delta p$) can be calculated from the average speed ($\bar{v}$) and the speed difference between surfaces ($\Delta v$) with the density ($\rho$) using

kyon

which allows us to see the effect of the average speed of a body and the difference between its surfaces, as observed in an airplane or bird wing.

The profile of the speed on a cylinder radio ($v$) in the radius of position in a tube ($r$) allows us to calculate the volume flow ($J_V$) in a tube by integrating over the entire surface, which leads us to the well-known Hagen-Poiseuille law.

image

The result is an equation that depends on ERROR:5417,0 raised to the fourth power. However, it is crucial to note that this flow profile only holds true in the case of laminar flow.

Thus, from the viscosity ($\eta$), it follows that the volume flow ($J_V$) before ERROR:5430.1 and ERROR:6673.1, the expression:

equation=3178

The original papers that gave rise to this law with a combined name were:

"Ueber die Gesetze, welche des der Strom des Wassers in r hrenf rmigen Gef ssen bestimmen" (On the laws governing the flow of water in cylindrical vessels), Gotthilf Hagen, Annalen der Physik und Chemie 46:423442 (1839).

"Recherches exp rimentales sur le mouvement des liquides dans les tubes de tr s-petits diam tres" (Experimental research on the movement of liquids in tubes of very small diameters), Jean-Louis-Marie Poiseuille, Comptes Rendus de l'Acad mie des Sciences 9:433544 (1840).

When solving the flow equation with the boundary condition, we obtain the speed on a cylinder radio ($v$) as a function of the curvature radio ($r$), represented by a parabola centered at the maximum flow rate ($v_{max}$) and equal to zero at the tube radius ($R$):

kyon.

The value of the maximum flow rate ($v_{max}$) at the center of a cylinder depends on the viscosity ($\eta$), the tube radius ($R$), and the gradient created by the pressure difference ($\Delta p_s$) and the tube length ($\Delta L$), as represented by:

kyon

The negative sign indicates that the flow always occurs in the direction opposite to the gradient, meaning from the area of higher pressure to the area of lower pressure.

La plaquita de arcilla sera arrastrada por la corriente en la medida que la fuerza hidrost tica dp,S supere la fuerza gravitacional mg, donde S es la secci n de la plaquita, m su masa, dp la diferencia de presi n entre la parte interior y superior de esta y g la aceleraci n gravitacional.

Por ello la condici n de ser arrastrada es:

kyon

La masa de la plaquita se puede calcular de la densidad solida del material y del volumen mediante\\n\\n

$m=\rho_sV$

\\n\\nEl volumen se calcula del cuadrado del lado l_c y la altura w_c de modo que\\n\\n

$V=w_cl_c^2$



Con ello la masa del la plaquita es:

kyon

La secci n S sobre la que act a la presi n sobre la plaquita se calcula del cuadrado del lado l_c de esta:

kyon

La condici n de estabilidad general

equation=4506

se puede reescribir con la masa

equation=4508

y la secci n

equation=4507

como

kyon


>Model

ID:(379, 0)