Skip to content

Commit

Permalink
changes vector notation and fixes typos
Browse files Browse the repository at this point in the history
  • Loading branch information
navidcy committed Mar 12, 2019
1 parent 6dd6f52 commit c19640b
Show file tree
Hide file tree
Showing 5 changed files with 53 additions and 54 deletions.
25 changes: 12 additions & 13 deletions docs/equations/ALE-algorithm.rst
Original file line number Diff line number Diff line change
Expand Up @@ -5,24 +5,24 @@ The semi-discrete, vertically integrated, Boussinesq hydrostatic equations of
motion in general-coordinate :math:`r` are

.. math::
D_t \vec{u} + f \hat{k} \wedge \vec{u} + \nabla_z \Phi + \frac{1}{\rho_o} \nabla_z p &= \nabla \cdot \vec{\underline{\tau}} \\
\rho \delta_k \Phi + \delta_k p &= 0 \\
\partial_t h + \nabla_r \cdot ( h \vec{u} ) + \delta_k ( z_r \dot{r} ) &= 0 \\
\partial_t h \theta + \nabla_r \cdot ( h \vec{u} \theta ) + \delta_k ( z_r \dot{r} \theta ) &= \nabla \cdot \vec{Q}_\theta \\
\partial_t h S + \nabla_r \cdot ( h \vec{u} S ) + \delta_k ( z_r \dot{r} S ) &= \nabla \cdot \vec{Q}_S \\
\rho &= \rho(S, \theta, z)
D_t \boldsymbol{u} + f \widehat{\boldsymbol{k}} \wedge \boldsymbol{u} + \boldsymbol{\nabla}_z \Phi + \frac{1}{\rho_o} \boldsymbol{\nabla}_z p &= \boldsymbol{\nabla} \cdot \boldsymbol{\underline{\tau}} ,\\
\rho \delta_k \Phi + \delta_k p &= 0 ,\\
\partial_t h + \nabla_r \cdot ( h \boldsymbol{u} ) + \delta_k ( z_r \dot{r} ) &= 0 ,\\
\partial_t h \theta + \nabla_r \cdot ( h \boldsymbol{u} \theta ) + \delta_k ( z_r \dot{r} \theta ) &= \boldsymbol{\nabla} \cdot \boldsymbol{Q}_\theta ,\\
\partial_t h S + \nabla_r \cdot ( h \boldsymbol{u} S ) + \delta_k ( z_r \dot{r} S ) &= \boldsymbol{\nabla} \cdot \boldsymbol{Q}_S ,\\
\rho &= \rho(S, \theta, z) .
The Arbitrary-Lagrangian-Eulerian algorithm we use is quasi-Lagrangian in
that in the first (Lagrangian) phase, regardless of the current mesh (or coordinate
:math:`r`) we integrate the equations forward with :math:`\dot{r}=0`, i.e.:

.. math::
D_t \vec{u} + f \hat{k} \wedge \vec{u} + \nabla_z \Phi + \frac{1}{\rho_o} \nabla_z p &= \nabla \cdot \vec{\underline{\tau}} \\
\rho \delta_k \Phi + \delta_k p &= 0 \\
\partial_t h + \nabla_r \cdot ( h \vec{u} ) &= 0 \\
\partial_t h \theta + \nabla_r \cdot ( h \vec{u} \theta ) &= \nabla \cdot \vec{Q}_\theta \\
\partial_t h S + \nabla_r \cdot ( h \vec{u} S ) &= \nabla \cdot \vec{Q}_S \\
\rho &= \rho(S, \theta, z)
D_t \boldsymbol{u} + f \widehat{\boldsymbol{k}} \wedge \boldsymbol{u} + \boldsymbol{\nabla}_z \Phi + \frac{1}{\rho_o} \boldsymbol{\nabla}_z p &= \boldsymbol{\nabla} \cdot \boldsymbol{\underline{\tau}} ,\\
\rho \delta_k \Phi + \delta_k p &= 0 ,\\
\partial_t h + \nabla_r \cdot ( h \boldsymbol{u} ) &= 0 ,\\
\partial_t (h \theta) + \nabla_r \cdot ( h \boldsymbol{u} \theta ) &= \boldsymbol{\nabla} \cdot \boldsymbol{Q}_\theta ,\\
\partial_t (h S) + \nabla_r \cdot ( h \boldsymbol{u} S ) &= \boldsymbol{\nabla} \cdot \boldsymbol{Q}_S ,\\
\rho &= \rho(S, \theta, z) .
Notice that by setting :math:`\dot{r}=0` all the terms with the metric
:math:`z_r` disappeared.
Expand All @@ -31,4 +31,3 @@ After a finite amount of time, the mesh (:math:`h`) may become very distorted
or unrelated to the intended mesh. At any point in time, we can simply define
a new mesh and remap from the current mesh to the new mesh without an
explicit change in the physical state.

12 changes: 6 additions & 6 deletions docs/equations/general_coordinate.rst
Original file line number Diff line number Diff line change
Expand Up @@ -9,9 +9,9 @@ The Boussinesq hydrostatic equations of motion in general-coordinate
:math:`r` are

.. math::
D_t \vec{u} + f \hat{k} \wedge \vec{u} + \nabla_z \Phi + \frac{1}{\rho_o} \nabla_z p &= \nabla \cdot \vec{\underline{\tau}} \\
\rho \partial_z \Phi + \partial_z p &= 0 \\
\partial_t z_r + \nabla_r \cdot ( z_r \vec{u} ) + \partial_r ( z_r \dot{r} ) &= 0 \\
\partial_t z_r \theta + \nabla_r \cdot ( z_r \vec{u} \theta ) + \partial_r ( z_r \dot{r} \theta ) &= \nabla \cdot \vec{Q}_\theta \\
\partial_t z_r S + \nabla_r \cdot ( z_r \vec{u} S ) + \partial_r ( z_r \dot{r} S ) &= \nabla \cdot \vec{Q}_S \\
\rho &= \rho(S, \theta, z)
D_t \boldsymbol{u} + f \widehat{\boldsymbol{k}} \wedge \boldsymbol{u} + \boldsymbol{\nabla}_z \Phi + \frac{1}{\rho_o} \boldsymbol{\nabla}_z p &= \boldsymbol{\nabla} \cdotp \boldsymbol{\underline{\tau}} ,\\
\rho \partial_z \Phi + \partial_z p &= 0 ,\\
\partial_t z_r + \nabla_r \cdotp ( z_r \boldsymbol{u} ) + \partial_r ( z_r \dot{r} ) &= 0 ,\\
\partial_t z_r \theta + \nabla_r \cdotp ( z_r \boldsymbol{u} \theta ) + \partial_r ( z_r \dot{r} \theta ) &= \boldsymbol{\nabla} \cdotp \boldsymbol{Q}_\theta ,\\
\partial_t z_r S + \nabla_r \cdotp ( z_r \boldsymbol{u} S ) + \partial_r ( z_r \dot{r} S ) &= \boldsymbol{\nabla} \cdotp \boldsymbol{Q}_S ,\\
\rho &= \rho(S, \theta, z) .
38 changes: 19 additions & 19 deletions docs/equations/governing.rst
Original file line number Diff line number Diff line change
Expand Up @@ -6,39 +6,39 @@ Governing equations
The Boussinesq hydrostatic equations of motion in height coordinates are

.. math::
D_t \vec{u} + f \hat{k} \wedge \vec{u} + \nabla_z \Phi + \frac{1}{\rho_o} \nabla_z p &= \nabla \cdot \vec{\underline{\tau}} \\
\rho \partial_z \Phi + \partial_z p &= 0 \\
\nabla_z \cdot \vec{u} + \partial_z w &= 0 \\
D_t \theta &= \nabla \cdot \vec{Q}_\theta \\
D_t S &= \nabla \cdot \vec{Q}_S \\
\rho &= \rho(S, \theta, z)
where notation is described in :ref:`equations-notation`. :math:`\vec{\underline{\tau}}` is the stress tensori and
:math:`\vec{Q}_\theta` and :math:`\vec{Q}_S` are fluxes of heat and salt respectively.
D_t \boldsymbol{u} + f \widehat{\boldsymbol{k}} \wedge \boldsymbol{u} + \boldsymbol{\nabla}_z \Phi + \frac{1}{\rho_o} \boldsymbol{\nabla}_z p &= \boldsymbol{\nabla} \cdotp \boldsymbol{\underline{\tau}} , \\
\rho \partial_z \Phi + \partial_z p &= 0 , \\
\boldsymbol{\nabla}_z \cdotp \boldsymbol{u} + \partial_z w &= 0 , \\
D_t \theta &= \boldsymbol{\nabla} \cdotp \boldsymbol{Q}_\theta , \\
D_t S &= \boldsymbol{\nabla} \cdotp \boldsymbol{Q}_S , \\
\rho &= \rho(S, \theta, z) ,
where notation is described in :ref:`equations-notation`. :math:`\boldsymbol{\underline{\tau}}` is the stress tensori and
:math:`\boldsymbol{Q}_\theta` and :math:`\boldsymbol{Q}_S` are fluxes of heat and salt respectively.


.. :ref:`vector_invariant`
The total derivative is

.. math::
D_t &\equiv \partial_t + \vec{v} \cdot \nabla \\
&= \partial_t + \vec{u} \cdot \nabla_z + w \partial_z
D_t & \equiv \partial_t + \boldsymbol{v} \cdotp \boldsymbol{\nabla} \\
&= \partial_t + \boldsymbol{u} \cdotp \boldsymbol{\nabla}_z + w \partial_z .
The non-divergence of flow allows a total derivative to be re-written in flux form:

.. math::
D_t \theta &= \partial_t + \nabla \cdot ( \vec{v} \theta ) \\
&= \partial_t + \nabla_z \cdot ( \vec{u} \theta ) + \partial_z ( w \theta )
D_t \theta &= \partial_t + \boldsymbol{\nabla} \cdotp ( \boldsymbol{v} \theta ) \\
&= \partial_t + \boldsymbol{\nabla}_z \cdotp ( \boldsymbol{u} \theta ) + \partial_z ( w \theta ) .
The above equations of motion can thus be written as:

.. math::
D_t \vec{u} + f \hat{k} \wedge \vec{u} + \nabla_z \Phi + \frac{1}{\rho_o} \nabla_z p &= \nabla \cdot \vec{\underline{\tau}} \\
\rho \partial_z \Phi + \partial_z p &= 0 \\
\nabla_z \cdot \vec{u} + \partial_z w &= 0 \\
\partial_t \theta + \nabla_z \cdot ( \vec{u} \theta ) + \partial_z ( w \theta ) &= \nabla \cdot \vec{Q}_\theta \\
\partial_t S + \nabla_z \cdot ( \vec{u} S ) + \partial_z ( w S ) &= \nabla \cdot \vec{Q}_S \\
\rho &= \rho(S, \theta, z)
D_t \boldsymbol{u} + f \widehat{\boldsymbol{k}} \wedge \boldsymbol{u} + \boldsymbol{\nabla}_z \Phi + \frac{1}{\rho_o} \boldsymbol{\nabla}_z p &= \boldsymbol{\nabla} \cdotp \boldsymbol{\underline{\tau}} ,\\
\rho \partial_z \Phi + \partial_z p &= 0 ,\\
\boldsymbol{\nabla}_z \cdotp \boldsymbol{u} + \partial_z w &= 0 ,\\
\partial_t \theta + \boldsymbol{\nabla}_z \cdotp ( \boldsymbol{u} \theta ) + \partial_z ( w \theta ) &= \boldsymbol{\nabla} \cdotp \boldsymbol{Q}_\theta ,\\
\partial_t S + \boldsymbol{\nabla}_z \cdotp ( \boldsymbol{u} S ) + \partial_z ( w S ) &= \nabla \cdotp \boldsymbol{Q}_S ,\\
\rho &= \rho(S, \theta, z) .
.. toctree::
vector_invariant_eqns
14 changes: 7 additions & 7 deletions docs/equations/notation.rst
Original file line number Diff line number Diff line change
Expand Up @@ -16,28 +16,28 @@ Horizontal components of velocity are indicated by :math:`u` and :math:`v` and v

:math:`p` is pressure and :math:`\Phi` is geo-potential:

.. math:
\Phi = g z
.. math::
\Phi = g z .
The thermodynamic state variables are usually salinity, :math:`S`, and potential temperature, :math:`\theta` or the absolute salinity and conservative temperature, depending on the equation of state. :math:`\rho` is in-situ density.

Vector notation
---------------

The three-dimensional velocity vector is denoted :math:`\vec{v}`
The three-dimensional velocity vector is denoted :math:`\boldsymbol{v}`

.. math::
\vec{v} = \vec{u} + \vec{k} w
\boldsymbol{v} = \boldsymbol{u} + \widehat{\boldsymbol{k}} w ,
where :math:`\vec{k}` is the unit vector pointed in the upward vertical direction and :math:`\vec{u} = (u,v,0)` is the horizontal
where :math:`\widehat{\boldsymbol{k}}` is the unit vector pointed in the upward vertical direction and :math:`\boldsymbol{u} = (u, v, 0)` is the horizontal
component of velocity normal to the vertical.

The gradient operator without a suffix is three dimensional:

.. math::
\nabla = ( \nabla_z, \partial_z ) .
\boldsymbol{\nabla} = ( \boldsymbol{\nabla}_z, \boldsymbol{\nabla}_z ) .
but a suffix indicates a lateral gradient along a surface of constant property indicated by the suffix:

.. math::
\nabla_z = \left( \left. \partial_x \right|_z, \left. \partial_y \right|_z, 0 \right) .
\boldsymbol{\nabla}_z = \left( \left. \partial_x \right|_z, \left. \partial_y \right|_z, 0 \right) .
18 changes: 9 additions & 9 deletions docs/equations/vector_invariant_eqns.rst
Original file line number Diff line number Diff line change
Expand Up @@ -8,18 +8,18 @@ MOM6 solve the momentum equations written in vector-invariant form.
An identity allows the total derivative of velocity to be written in the vector-invariant form:

.. math::
D_t \vec{u} &= \partial_t \vec{u} + \vec{v} \cdot \nabla \vec{u} \\
&= \partial_t \vec{u} + \vec{u} \cdot \nabla_z \vec{u} + w \partial_z \vec{u} \\
&= \partial_t \vec{u} + \left( \nabla \wedge \vec{u} \right) \wedge \vec{v} + \nabla \frac{1}{2} \left|\vec{u}\right|^2
D_t \boldsymbol{u} &= \partial_t \boldsymbol{u} + \boldsymbol{v} \cdotp \boldsymbol{\nabla} \boldsymbol{u} \\
&= \partial_t \boldsymbol{u} + \boldsymbol{u} \cdotp \boldsymbol{\nabla}_z \boldsymbol{u} + w \partial_z \boldsymbol{u} \\
&= \partial_t \boldsymbol{u} + \left( \boldsymbol{\nabla} \wedge \boldsymbol{u} \right) \wedge \boldsymbol{v} + \boldsymbol{\nabla} \underbrace{\frac{1}{2} \left|\boldsymbol{u}\right|^2}_{\equiv K} .
The flux-form equations of motion in height coordinates can thus be written succinctly as:

.. math::
\partial_t \vec{u} + \left( f \hat{k} + \nabla \wedge \vec{u} \right) \wedge \vec{v} + \nabla K
+ \frac{\rho}{\rho_o} \nabla \Phi + \frac{1}{\rho_o} \nabla p &= \nabla \cdot \vec{\underline{\tau}} \\
\nabla_z \cdot \vec{u} + \partial_z w &= 0 \\
\partial_t \theta + \nabla_z \cdot ( \vec{u} \theta ) + \partial_z ( w \theta ) &= \nabla \cdot \vec{Q}_\theta \\
\partial_t S + \nabla_z \cdot ( \vec{u} S ) + \partial_z ( w S ) &= \nabla \cdot \vec{Q}_S \\
\rho &= \rho(S, \theta, z)
\partial_t \boldsymbol{u} + \left( f \widehat{\boldsymbol{k}} + \boldsymbol{\nabla} \wedge \boldsymbol{u} \right) \wedge \boldsymbol{v} + \boldsymbol{\nabla} K
+ \frac{\rho}{\rho_o} \boldsymbol{\nabla} \Phi + \frac{1}{\rho_o} \boldsymbol{\nabla} p &= \boldsymbol{\nabla} \cdotp \boldsymbol{\underline{\tau}} ,\\
\boldsymbol{\nabla}_z \cdotp \boldsymbol{u} + \partial_z w &= 0 ,\\
\partial_t \theta + \boldsymbol{\nabla}_z \cdotp ( \boldsymbol{u} \theta ) + \partial_z ( w \theta ) &= \boldsymbol{\nabla} \cdotp \boldsymbol{Q}_\theta ,\\
\partial_t S + \boldsymbol{\nabla}_z \cdotp ( \boldsymbol{u} S ) + \partial_z ( w S ) &= \boldsymbol{\nabla} \cdotp \boldsymbol{Q}_S ,\\
\rho &= \rho(S, \theta, z) ,
where the horizontal momentum equations and vertical hydrostatic balance equation have been written as a single three-dimensional equation.

0 comments on commit c19640b

Please sign in to comment.