Deep water mixing process

Storyboard

In the case of greater depths, the energy dissipation mechanisms of vortices are related to viscosity and buoyancy. Which one dominates depends on the situation and can be determined using characteristic numbers associated with both phenomena.

[1] Marine Physics, Jerzy Dera, Elsevier, 1992 (6.2 The Turbulent Exchange of Mass, Heat and Momentum in the Sea)

>Model

ID:(1628, 0)



Deep water mixing process

Storyboard

In the case of greater depths, the energy dissipation mechanisms of vortices are related to viscosity and buoyancy. Which one dominates depends on the situation and can be determined using characteristic numbers associated with both phenomena. [1] Marine Physics, Jerzy Dera, Elsevier, 1992 (6.2 The Turbulent Exchange of Mass, Heat and Momentum in the Sea)

Variables

Symbol
Text
Variable
Value
Units
Calculate
MKS Value
MKS Units
$\tau$
tau
Characteristic time
s
$\Delta\rho$
Drho
Density variation
kg/m^3
$\epsilon_{\rho}$
epsilon_rho
Energy dissipated by flotation
J
$\epsilon_{\eta}$
epsilon_eta
Energy dissipated by viscosity
J
$\epsilon_v$
epsilon_v
Kinetic energy
J
$\rho$
rho
Medium density
kg/m^3
$l$
l
Mixing length
m
$Re$
Re
Reynolds number
-
$R_i$
R_i
Richardson number
-
$l$
l
Tamaño característico
m
$\eta$
eta
Viscosity of ocean water
Pa s
$v_l$
v_l
Vortex speed
m/s

Calculations


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

Symbol
Equation
Solved
Translated

Calculations

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Equation
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Equations

The loss from the vortices involves the energy dissipated by viscosity ($\epsilon_{\eta}$) with the viscosity of ocean water ($\eta$), the vortex speed ($v_l$), and the mixing length ($l$).

$\epsilon_{\eta} =\eta\displaystyle\frac{v_l}{l}$



The energy loss due to the characteristic time ($\tau$), which is

equation=12206

is described by

equation

Since the energy dissipated by flotation ($\epsilon_{\rho}$) equals ERROR:9484, the gravitational Acceleration ($g$), and the distance traveled ($\Delta z$),

$\epsilon_{\rho} =\Delta\rho g \Delta z$



the energy loss will be this energy per the characteristic time ($\tau$), which, with the mixing length ($l$), is

equation=12206

so with the vortex speed ($v_l$), it is

equation

In the case where diffusive processes are more relevant than buoyancy, we have that with the kinetic energy ($\epsilon_v$), the energy dissipated by flotation ($\epsilon_{\rho}$) and the energy dissipated by viscosity ($\epsilon_{\eta}$),

$\epsilon_v > \epsilon_{\eta} \gg \epsilon_{\rho}$



Given that with the characteristic time ($\tau$), the kinetic energy ($\epsilon_v$) and the medium density ($\rho$) is

equation=12212

and the energy dissipated by viscosity ($\epsilon_{\eta}$) is

equation=12207

the existence of the vortex implies that its kinetic energy is greater than the loss, so with

$\rho\displaystyle\frac{v_l^3}{l}>\eta\displaystyle\frac{v_l^2}{l^2}$



the requirement that the reynolds number ($Re$) must be

equation

In the event that with the kinetic energy ($\epsilon_v$), the energy dissipated by viscosity ($\epsilon_{\eta}$), and the energy dissipated by flotation ($\epsilon_{\rho}$) are such that

$\epsilon_v > \epsilon_{\rho} \gg \epsilon_{\eta}$



Given that the kinetic energy ($\epsilon_v$) is with the medium density ($\rho$), the mixing length ($l$), and the vortex speed ($v_l$) in the characteristic time ($\tau$),

equation=12212

and the energy dissipated by flotation ($\epsilon_{\rho}$) is with ERROR:9484, the gravitational Acceleration ($g$), and the vortex speed ($v_l$) in the characteristic time ($\tau$),

equation=12208

the existence of the vortex implies that its kinetic energy is greater than the loss, so with

$\rho\displaystyle\frac{v_l^3}{l}>\Delta\rho g v_l$



the requirement arises that with, the richardson number ($R_i$) must satisfy

equation

Como the kinetic energy ($\epsilon_v$) of the vortices depends on the medium density ($\rho$) and the vortex speed ($v_l$) according to

$\epsilon_v =\displaystyle\frac{1}{2}\rho v_l^2\sim \rho v_l^2$



Como the characteristic time ($\tau$) with the mixing length ($l$) is

equation=12206

we have that

$\displaystyle\frac{\epsilon_v}{\tau} =\rho \displaystyle\frac{v_l^3}{l}$



which means

equation


Examples


mechanisms

In general, energy dissipation occurs over the considered time period, so the kinetic energy ($\epsilon_v$) should be compared with a characteristic time ($\tau$) such that

$\displaystyle\frac{d\epsilon}{dt}\sim\displaystyle\frac{\epsilon_v}{\tau}$



There are two types of processes that reduce the energy of vortices until they become thermal fluctuations. On one hand, there's momentum diffusion or viscosity, while on the other hand, there's flotation.

The loss of the kinetic energy ($\epsilon_v$) varies depending on the energy dissipated by viscosity ($\epsilon_{\eta}$) and the energy dissipated by flotation ($\epsilon_{\rho}$) in the characteristic time ($\tau$) as

equation=12205

As the kinetic energy ($\epsilon_v$), where for simplicity we neglect the factor of 1/2 and it depends on the medium density ($\rho$) and the vortex speed ($v_l$),

$\epsilon =\displaystyle\frac{1}{2}\rho v_l^2\sim \rho v_l^2$



the energy loss will be this energy by the characteristic time ($\tau$), which with the mixing length ($l$) is

equation=12206

and thus, the variation is

equation=12212

As the energy dissipated by viscosity ($\epsilon_{\eta}$) is with the viscosity of ocean water ($\eta$), the vortex speed ($v_l$), and the mixing length ($l$),

$\epsilon_{\eta} =\eta\displaystyle\frac{v_l}{l}$



the energy loss will be this energy by the characteristic time ($\tau$), which with the mixing length ($l$) is

equation=12206

and thus, the variation is

equation=12207

As the energy dissipated by flotation ($\epsilon_{\rho}$) is with ERROR:9484, the gravitational acceleration ($g$), and the mixing length ($l$):

$\epsilon_{\rho} =\Delta\rho g l$



the energy loss will be this energy by the characteristic time ($\tau$), which is

equation=12206

and thus, the variation is

equation=12208

In the case where diffusive processes are more relevant than flotation ones, it is observed that with the kinetic energy ($\epsilon_v$), the energy dissipated by flotation ($\epsilon_{\rho}$), and the energy dissipated by viscosity ($\epsilon_{\eta}$),

$\epsilon_v > \epsilon_{\eta} \gg \epsilon_{\rho}$



Given that with the characteristic time ($\tau$), the kinetic energy ($\epsilon_v$) is

equation=12212

and the energy dissipated by viscosity ($\epsilon_{\eta}$) is

equation=12207

the existence of the vortex implies that its kinetic energy is greater than the loss, so with

$\rho\displaystyle\frac{v_l^3}{l}>\eta\displaystyle\frac{v_l^2}{l^2}$



it results in the requirement that it must be the case that

equation=12209

In the event that with the kinetic energy ($\epsilon_v$), the energy dissipated by viscosity ($\epsilon_{\eta}$), and the energy dissipated by flotation ($\epsilon_{\rho}$) are such that

$\epsilon_v > \epsilon_{\rho} \gg \epsilon_{\eta}$



Given that the kinetic energy ($\epsilon_v$) is with the density ($\rho$), the mixing length ($l$), and the vortex speed ($v_l$) in the characteristic time ($\tau$),

equation=12212

and the energy dissipated by flotation ($\epsilon_{\rho}$) is with ERROR:9484, the gravitational Acceleration ($g$), and the vortex speed ($v_l$) in the characteristic time ($\tau$),

equation=12208

the existence of the vortex implies that its kinetic energy is greater than the loss, so with

$\rho\displaystyle\frac{v_l^3}{l}>\Delta\rho g v_l$



the requirement arises that with it must be the case that the richardson number ($R_i$) satisfies

equation=12210

The relationship between ERROR:8614 with the density ($\rho$), the vortex speed ($v_l$), the viscosity of ocean water ($\eta$), and the tamaño característico ($l$) is given by

equation=12209

and the richardson number ($R_i$) with ERROR:9484 and the gravitational Acceleration ($g$) is represented by

equation=12210

as shown in the graph below, where both boundary cases mark the stability limit situations:

image


model

There are two types of processes that reduce the energy of vortices until they become thermal fluctuations. On one hand, there's momentum diffusion or viscosity, while on the other hand, there's flotation.

The loss of the kinetic energy ($\epsilon_v$) varies depending on the energy dissipated by viscosity ($\epsilon_{\eta}$) and the energy dissipated by flotation ($\epsilon_{\rho}$) in the characteristic time ($\tau$) as

kyon

With the vortex speed ($v_l$) and the mixing length ($l$), one can define a characteristic time ($\tau$), which allows estimating the energy loss both due to viscosity and flotation.

Therefore, it follows that

kyon

The variation of the kinetic energy ($\epsilon_v$) in the characteristic time ($\tau$) is proportional to the kinetic energy, which depends on the medium density ($\rho$) and the vortex speed ($v_l$), divided by the characteristic time ($\tau$). Since this is a function of the mixing length ($l$), it follows that:

kyon

The loss due to water viscosity can be calculated directly from the viscous force and the path traveled by the vortex.

The loss of the energy dissipated by viscosity ($\epsilon_{\eta}$) varies depending on the viscosity of ocean water ($\eta$), the vortex speed ($v_l$), and the mixing length ($l$). In the characteristic time ($\tau$), it is expressed as

kyon

The loss due to buoyancy can be calculated directly from the lift force and the distance traveled by the vortex.

The loss of the energy dissipated by flotation ($\epsilon_{\rho}$) varies depending on ERROR:9484, the gravitational Acceleration ($g$), and the vortex speed ($v_l$). In the characteristic time ($\tau$), it is expressed as

kyon

In the event that with the kinetic energy ($\epsilon_v$), the energy dissipated by viscosity ($\epsilon_{\eta}$), and the energy dissipated by flotation ($\epsilon_{\rho}$) are such that

$\epsilon_v > \epsilon_{\eta} \gg \epsilon_{\rho}$



the damping is primarily due to viscosity.

In that case, a condition is obtained for the reynolds number ($Re$), which is a function of the medium density ($\rho$), the vortex speed ($v_l$), the tamaño característico ($l$), and the viscosity of ocean water ($\eta$), which must satisfy

kyon

In the event that with the kinetic energy ($\epsilon_v$), the energy dissipated by viscosity ($\epsilon_{\eta}$), and the energy dissipated by flotation ($\epsilon_{\rho}$) are such that

$\epsilon_v > \epsilon_{\rho} \gg \epsilon_{\eta}$



the damping is primarily due to buoyancy.

In that case, a condition is obtained for the richardson number ($R_i$), which is a function of ERROR:9484, the medium density ($\rho$), the vortex speed ($v_l$), the gravitational Acceleration ($g$), and the mixing length ($l$), which must satisfy

kyon


>Model

ID:(1628, 0)



Mechanisms

Definition


ID:(15616, 0)



Kinetic energy dissipated by the vortex

Image

In general, energy dissipation occurs over the considered time period, so the kinetic energy ($\epsilon_v$) should be compared with a characteristic time ($\tau$) such that

$\displaystyle\frac{d\epsilon}{dt}\sim\displaystyle\frac{\epsilon_v}{\tau}$



There are two types of processes that reduce the energy of vortices until they become thermal fluctuations. On one hand, there's momentum diffusion or viscosity, while on the other hand, there's flotation.

The loss of the kinetic energy ($\epsilon_v$) varies depending on the energy dissipated by viscosity ($\epsilon_{\eta}$) and the energy dissipated by flotation ($\epsilon_{\rho}$) in the characteristic time ($\tau$) as

ID:(15621, 0)



Variation of kinetic energy

Note

As the kinetic energy ($\epsilon_v$), where for simplicity we neglect the factor of 1/2 and it depends on the medium density ($\rho$) and the vortex speed ($v_l$),

$\epsilon =\displaystyle\frac{1}{2}\rho v_l^2\sim \rho v_l^2$



the energy loss will be this energy by the characteristic time ($\tau$), which with the mixing length ($l$) is



and thus, the variation is

ID:(15608, 0)



Loss of energy due to viscosity

Quote

As the energy dissipated by viscosity ($\epsilon_{\eta}$) is with the viscosity of ocean water ($\eta$), the vortex speed ($v_l$), and the mixing length ($l$),

$\epsilon_{\eta} =\eta\displaystyle\frac{v_l}{l}$



the energy loss will be this energy by the characteristic time ($\tau$), which with the mixing length ($l$) is



and thus, the variation is

ID:(15609, 0)



Loss of energy due to flotation

Exercise

As the energy dissipated by flotation ($\epsilon_{\rho}$) is with ERROR:9484, the gravitational acceleration ($g$), and the mixing length ($l$):

$\epsilon_{\rho} =\Delta\rho g l$



the energy loss will be this energy by the characteristic time ($\tau$), which is



and thus, the variation is

ID:(15610, 0)



Viscosity damping

Equation

In the case where diffusive processes are more relevant than flotation ones, it is observed that with the kinetic energy ($\epsilon_v$), the energy dissipated by flotation ($\epsilon_{\rho}$), and the energy dissipated by viscosity ($\epsilon_{\eta}$),

$\epsilon_v > \epsilon_{\eta} \gg \epsilon_{\rho}$



Given that with the characteristic time ($\tau$), the kinetic energy ($\epsilon_v$) is



and the energy dissipated by viscosity ($\epsilon_{\eta}$) is



the existence of the vortex implies that its kinetic energy is greater than the loss, so with

$\rho\displaystyle\frac{v_l^3}{l}>\eta\displaystyle\frac{v_l^2}{l^2}$



it results in the requirement that it must be the case that

ID:(15612, 0)



Flotation damping

Script

In the event that with the kinetic energy ($\epsilon_v$), the energy dissipated by viscosity ($\epsilon_{\eta}$), and the energy dissipated by flotation ($\epsilon_{\rho}$) are such that

$\epsilon_v > \epsilon_{\rho} \gg \epsilon_{\eta}$



Given that the kinetic energy ($\epsilon_v$) is with the density ($\rho$), the mixing length ($l$), and the vortex speed ($v_l$) in the characteristic time ($\tau$),



and the energy dissipated by flotation ($\epsilon_{\rho}$) is with ERROR:9484, the gravitational Acceleration ($g$), and the vortex speed ($v_l$) in the characteristic time ($\tau$),



the existence of the vortex implies that its kinetic energy is greater than the loss, so with

$\rho\displaystyle\frac{v_l^3}{l}>\Delta\rho g v_l$



the requirement arises that with it must be the case that the richardson number ($R_i$) satisfies

ID:(15611, 0)



Richardson and Reynolds number relationship

Variable

The relationship between ERROR:8614 with the density ($\rho$), the vortex speed ($v_l$), the viscosity of ocean water ($\eta$), and the tamaño característico ($l$) is given by



and the richardson number ($R_i$) with ERROR:9484 and the gravitational Acceleration ($g$) is represented by



as shown in the graph below, where both boundary cases mark the stability limit situations:

Turbulent Coherent Structures in a Thermally stable Boundary Layer, Owen Williams and Alexander J. Smits, https://www.researchgate.net/publication/228761589_Turbulent_Coherent_Structures_in_a_Thermally_Stable_Boundary_Layer

ID:(12211, 0)



Model

Audio


ID:(15620, 0)