From 4c7218ec40df73af742add8d577d4c635415f0a2 Mon Sep 17 00:00:00 2001 From: Jordan Musser Date: Thu, 23 Apr 2026 13:49:02 -0400 Subject: [PATCH 1/2] Initial pass at reference frame docs --- .../user_guide/inputs/boundary_conditions.rst | 12 +++++++ docs/source_docs/user_guide/inputs/domain.rst | 34 +++++++++++++++++++ .../user_guide/inputs/initial_conditions.rst | 18 ++++++++++ 3 files changed, 64 insertions(+) diff --git a/docs/source_docs/user_guide/inputs/boundary_conditions.rst b/docs/source_docs/user_guide/inputs/boundary_conditions.rst index 0a899de..7474e4a 100644 --- a/docs/source_docs/user_guide/inputs/boundary_conditions.rst +++ b/docs/source_docs/user_guide/inputs/boundary_conditions.rst @@ -35,6 +35,18 @@ The type of the boundary conditions in the BC region must be defined with the pr | | contained EBs | | | +---------------------+-----------------------------------------------------------------------+-------------+-----------+ +For each boundary condition the reference frame is defined using the prefix ``bc.[region_name]``: + ++-----------------------+------------------------------------------------------------------------+----------+----------+ +| | Description | Type | Default | ++=======================+========================================================================+==========+==========+ +| reference_frame | Specifies the reference frame used to interpret velocity components. | String | inertial | +| | | | | +| | Options: | | | +| | * ``inertial``: A static (laboratory) reference frame. | | | +| | * ``rotating``: Velocity is interpreted relateive to the rotating | | | +| | frame appropriately transformed when applied. | | | ++-----------------------+------------------------------------------------------------------------+----------+----------+ Fluid settings diff --git a/docs/source_docs/user_guide/inputs/domain.rst b/docs/source_docs/user_guide/inputs/domain.rst index 800d634..81002ac 100644 --- a/docs/source_docs/user_guide/inputs/domain.rst +++ b/docs/source_docs/user_guide/inputs/domain.rst @@ -112,3 +112,37 @@ The following inputs are defined using the prefix ``mfix``: +--------------------------+----------------------------------------------------------------------------+----------+---------+ | delp | Pressure drop (Pa) | Real | 0 | +--------------------------+----------------------------------------------------------------------------+----------+---------+ + + +Reference frame +--------------- + +MFIX‑Exa supports simulations in either an inertial (laboratory) reference frame or a uniformly rotating reference frame. The +choice of reference frame affects how momentum equations are solved and whether additional pseudo‑forces (Coriolis and +centrifugal) are included in the fluid and solids momentum balances. + +The following inputs are defined using the prefix ``mfix``: + ++--------------------------+----------------------------------------------------------------------------+----------+----------+ +| | Description | Type | Default | ++==========================+============================================================================+==========+==========+ +| reference_frame | Specifies the reference frame in which the governing equations are | String | inertial | +| | evaluated. | | | +| | | | | +| | Options: | | | +| | * ``inertial``: A static (laboratory) reference frame. | | | +| | * ``rotating``: A uniformly rotating frame. | | | ++--------------------------+----------------------------------------------------------------------------+----------+----------+ + + +The following inputs are defined using the prefix ``rotating_reference_frame``: + ++--------------------------+----------------------------------------------------------------------------+----------+----------+ +| | Description | Type | Default | ++==========================+============================================================================+==========+==========+ +| axis | The direction of the rotation axis in physical space. | Reals<3> | None | ++--------------------------+----------------------------------------------------------------------------+----------+----------+ +| axis_point | The location through which the rotation axis passes. | Reals<3> | None | ++--------------------------+----------------------------------------------------------------------------+----------+----------+ +| angular_speed | Scalar angular speed of the rotating frame, in radians per second. | Real | None | ++--------------------------+----------------------------------------------------------------------------+----------+----------+ diff --git a/docs/source_docs/user_guide/inputs/initial_conditions.rst b/docs/source_docs/user_guide/inputs/initial_conditions.rst index f996a7f..5a0d30d 100644 --- a/docs/source_docs/user_guide/inputs/initial_conditions.rst +++ b/docs/source_docs/user_guide/inputs/initial_conditions.rst @@ -17,6 +17,24 @@ The following inputs are defined using the prefix ``ic``: +-----------------------+------------------------------------------------------------------------+-------------+-----------+ +For each initial condition region the reference frame is defined using the prefix ``ic.[region_name]``: + ++-----------------------+------------------------------------------------------------------------+----------+----------+ +| | Description | Type | Default | ++=======================+========================================================================+==========+==========+ +| reference_frame | Specifies the reference frame used to interpret velocity components | String | inertial | +| | and initialize the flow field within the given initial‑condition | | | +| | region. | | | +| | | | | +| | Options: | | | +| | | | | +| | * ``inertial``: A static (laboratory) reference frame. | | | +| | * ``rotating``: Velocity fields specified in the region are | | | +| | interpreted relative to the rotating frame, and internally applies | | | +| | the appropriate transformation. | | | ++-----------------------+------------------------------------------------------------------------+----------+----------+ + + Fluid settings ~~~~~~~~~~~~~~ -- GitLab From 07dbfd57441ce968832c64c378ea05596ad3d107 Mon Sep 17 00:00:00 2001 From: Jordan Musser Date: Sat, 2 May 2026 15:26:14 -0400 Subject: [PATCH 2/2] Fix reference frame base --- docs/source_docs/user_guide/inputs/domain.rst | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/docs/source_docs/user_guide/inputs/domain.rst b/docs/source_docs/user_guide/inputs/domain.rst index 81002ac..d5eb974 100644 --- a/docs/source_docs/user_guide/inputs/domain.rst +++ b/docs/source_docs/user_guide/inputs/domain.rst @@ -135,7 +135,7 @@ The following inputs are defined using the prefix ``mfix``: +--------------------------+----------------------------------------------------------------------------+----------+----------+ -The following inputs are defined using the prefix ``rotating_reference_frame``: +The following inputs are defined using the prefix ``reference_frame``: +--------------------------+----------------------------------------------------------------------------+----------+----------+ | | Description | Type | Default | -- GitLab