diff --git a/docs/source_docs/refs.bib b/docs/source_docs/refs.bib
index 57e965dae16f6a98ac840ef4288e33c8631c2ecd..714645f65ebaa2027b9070312c1f69347d003838 100644
--- a/docs/source_docs/refs.bib
+++ b/docs/source_docs/refs.bib
@@ -499,6 +499,15 @@ doi = {https://doi.org/10.1016/j.jcp.2022.111305},
   publisher = {Taylor \& Francis},
 }
 
+@article{syam88,
+  author = {M. Syamlal and T.J. O'Brien},
+  title = {Simulation of granular layer inversion in liquid fluidized beds},
+  journal = {International Journal of Multiphase Flow},
+  volume = {14},
+  number = {4},
+  pages = {473-481},
+  year = {1988}
+}
 
 @article{tang15,
    author = {Tang, Y. and Peters, E. A. J. F. and Kuipers, J. A. M. and Kriebitzsch, S. H. L. and van der Hoef, M. A.},
diff --git a/docs/source_docs/user_guide/inputs/model_options.rst b/docs/source_docs/user_guide/inputs/model_options.rst
index 8057e4a91687c9e0e467c7c8fd3af52cd73fbdf1..c6e3dade4d8a69f4405cdf888768d212014c22e6 100644
--- a/docs/source_docs/user_guide/inputs/model_options.rst
+++ b/docs/source_docs/user_guide/inputs/model_options.rst
@@ -288,22 +288,31 @@ The following inputs are defined using the ``mfix`` prefix.
 
 
 
-Drag models
------------
+Fluid-particle drag
+-------------------
 
 The following input is defined using the ``mfix`` prefix.
 
-+-------------------+-----------------------------------------------------------------------+-------------+-----------+
-|                   | Description                                                           |   Type      | Default   |
-+===================+=======================================================================+=============+===========+
-| drag_type         | Fluid-particle drag model.                                            | String      | None      |
-|                   |                                                                       |             |           |
-|                   | * ``WenYu`` :cite:p:`Wen66`                                           |             |           |
-|                   | * ``Gidaspow`` :cite:p:`ding90,Lat00`                                 |             |           |
-|                   | * ``BVK2`` :cite:p:`Bee07,Bee071,tenneti11,tang15`                    |             |           |
-|                   | * ``UserDrag``                                                        |             |           |
-|                   |                                                                       |             |           |
-+-------------------+-----------------------------------------------------------------------+-------------+-----------+
++--------------------------+-----------------------------------------------------------------------+-------------+-----------+
+|                          | Description                                                           |   Type      | Default   |
++==========================+=======================================================================+=============+===========+
+| model                    | Fluid-particle drag model.                                            | String      | None      |
+|                          |                                                                       |             |           |
+|                          | * ``WenYu`` :cite:p:`Wen66`                                           |             |           |
+|                          | * ``Gidaspow`` :cite:p:`ding90,Lat00`                                 |             |           |
+|                          | * ``BVK2`` :cite:p:`Bee07,Bee071,tenneti11,tang15`                    |             |           |
+|                          | * ``SyamOBrien`` :cite:p:`syam88`                                     |             |           |
+|                          | * ``UserDrag``                                                        |             |           |
+|                          |                                                                       |             |           |
++--------------------------+-----------------------------------------------------------------------+-------------+-----------+
+| model.SyamOBrien.c1      | Fitting parameters for ``SyamOBrien`` drag model                      | Real        | None      |
+| model.SyamOBrien.d1      |                                                                       |             |           |
++--------------------------+-----------------------------------------------------------------------+-------------+-----------+
+| include_divtau           | Interpolate the fluid shear stress to particles and include in the    | int         | 0         |
+|                          | fluid-particle drag force. The force is applied to the fluid by       |             |           |
+|                          | multiplying the shear stress by fluid volume fraction.                |             |           |
++--------------------------+-----------------------------------------------------------------------+-------------+-----------+
+
 
 .. note::
 
@@ -315,14 +324,15 @@ The following input is defined using the ``mfix`` prefix.
 Heat transfer coefficients
 --------------------------
 
-The following input is defined using the ``mfix`` prefix.
-
-+-------------------+-----------------------------------------------------------------------+-------------+-----------+
-|                   | Description                                                           |   Type      | Default   |
-+===================+=======================================================================+=============+===========+
-| convection_type   | Fluid-particle heat transfer coefficient model.                       | String      | None      |
-|                   |                                                                       |             |           |
-|                   | * ``RanzMarshall`` :cite:p:`ranz52`                                   |             |           |
-|                   | * ``Gunn`` :cite:p:`gunn78`                                           |             |           |
-|                   |                                                                       |             |           |
-+-------------------+-----------------------------------------------------------------------+-------------+-----------+
+The following input is defined using the ``mfix.convection`` prefix.
+
++-------------------+-----------------------------------------------------------------------+-------------+--------------+
+|                   | Description                                                           |   Type      |  Default     |
++===================+=======================================================================+=============+==============+
+| model             | Fluid-particle heat transfer coefficient model.                       | String      | RanzMarshall |
+|                   |                                                                       |             |              |
+|                   | * ``RanzMarshall`` :cite:p:`ranz52`                                   |             |              |
+|                   | * ``Gunn`` :cite:p:`gunn78`                                           |             |              |
+|                   | * ``NullConvection`` - disable fluid-particle heat transfer           |             |              |
+|                   |                                                                       |             |              |
++-------------------+-----------------------------------------------------------------------+-------------+--------------+