diff --git a/documentation/svfsiplus/developer-guide/commod_class/readme.md b/documentation/svfsiplus/developer-guide/commod_class/readme.md
index 188f6ba..38295bb 100644
--- a/documentation/svfsiplus/developer-guide/commod_class/readme.md
+++ b/documentation/svfsiplus/developer-guide/commod_class/readme.md
@@ -10,7 +10,8 @@ The <a href="https://github.com/SimVascular/svFSIplus/blob/main/Code/Source/svFS
 <li> <a href="https://github.com/SimVascular/svFSIplus/blob/f424b7c9d1e575bc5804293bb4c4181a725561cd/Code/Source/svFSI/ComMod.h#L296"> bfType </a>  -  Body force </li>
 <li> <a href="https://github.com/SimVascular/svFSIplus/blob/f424b7c9d1e575bc5804293bb4c4181a725561cd/Code/Source/svFSI/ComMod.h#L326"> fibStrsType </a>  - Fiber stress </li>
 <li> <a href="https://github.com/SimVascular/svFSIplus/blob/f424b7c9d1e575bc5804293bb4c4181a725561cd/Code/Source/svFSI/ComMod.h#L342"> stModelType </a>  - Structural model </li>
-<li> <a href="https://github.com/SimVascular/svFSIplus/blob/f424b7c9d1e575bc5804293bb4c4181a725561cd/Code/Source/svFSI/ComMod.h#L389"> viscModelType </a>  - Fluid viscosity model </li>
+<li> <a href="https://github.com/SimVascular/svFSIplus/blob/f754c50ee0c8fbea28556d61b35da1f24a2df72a/Code/Source/svFSI/ComMod.h#L389"> fluidViscModelType </a>  - Fluid viscosity model </li>
+<li> <a href="https://github.com/SimVascular/svFSIplus/blob/f754c50ee0c8fbea28556d61b35da1f24a2df72a/Code/Source/svFSI/ComMod.h#L414"> solidViscModelType </a>  - Solid viscosity model </li>
 <li> <a href="https://github.com/SimVascular/svFSIplus/blob/f424b7c9d1e575bc5804293bb4c4181a725561cd/Code/Source/svFSI/ComMod.h#L415"> dmnType </a>  - Domain </li>
 <li> <a href="https://github.com/SimVascular/svFSIplus/blob/f424b7c9d1e575bc5804293bb4c4181a725561cd/Code/Source/svFSI/ComMod.h#L447"> adjType </a> - Mesh adjacency (neighboring element for each element) </li>
 <li> <a href="https://github.com/SimVascular/svFSIplus/blob/f424b7c9d1e575bc5804293bb4c4181a725561cd/Code/Source/svFSI/ComMod.h#L501> faceType </a> - Surface boundary  </li>
diff --git a/documentation/svfsiplus/developer-guide/implementation/readme.md b/documentation/svfsiplus/developer-guide/implementation/readme.md
index 722e414..0d024ad 100644
--- a/documentation/svfsiplus/developer-guide/implementation/readme.md
+++ b/documentation/svfsiplus/developer-guide/implementation/readme.md
@@ -507,7 +507,9 @@ Distribute domain properties
 <div style="background-color: #F0F0F0; padding: 10px; border: 1px solid #0000e6; border-left: 6px solid #0000e6">
 Distribute material properties [ <a href="https://github.com/SimVascular/svFSIplus/blob/main/Code/Source/svFSI/distribute.cpp#L1063"> dist_mat_consts</a> ]
 
-Distribute viscosity model properties [ <a href="https://github.com/SimVascular/svFSIplus/blob/main/Code/Source/svFSI/distribute.cpp#L1069"> dist_visc_model </a> ]
+Distribute fluid viscosity model properties [ <a href="https://github.com/SimVascular/svFSIplus/blob/f754c50ee0c8fbea28556d61b35da1f24a2df72a/Code/Source/svFSI/distribute.cpp#L1070"> dist_fluid_visc_model </a> ]
+
+Distribute solid viscosity model properties [ <a href="https://github.com/SimVascular/svFSIplus/blob/f754c50ee0c8fbea28556d61b35da1f24a2df72a/Code/Source/svFSI/distribute.cpp#L1064"> dist_solid_visc_model </a> ]
 </div> 
 
 Distribute cardiac electromechanics parameters<br>
diff --git a/documentation/svfsiplus/solver-input-file/domain_parameters/readme.md b/documentation/svfsiplus/solver-input-file/domain_parameters/readme.md
index dac09ea..ed04188 100755
--- a/documentation/svfsiplus/solver-input-file/domain_parameters/readme.md
+++ b/documentation/svfsiplus/solver-input-file/domain_parameters/readme.md
@@ -150,7 +150,6 @@ linear elasticity, structural or structural velocity pressure parameters.
 <a href="#domain_Force_y"> Force_y <a>
 <a href="#domain_Force_z"> Force_z <a>
 <a href="#domain_Poisson_ratio"> Poisson_ratio <a>
-<a href="#viscosity_parameters"> Viscosity <a>
 </pre>
 
 <!-- ---------- structural_velocity_pressure domain Parameters ---------- -->
@@ -164,7 +163,6 @@ linear elasticity, structural or structural velocity pressure parameters.
 <a href="#domain_Force_z"> Force_z <a>
 <a href="#domain_Momentum_stabilization_coefficient"> Momentum_stabilization_coefficient <a>
 <a href="#domain_Poisson_ratio"> Poisson_ratio <a>
-<a href="#viscosity_parameters"> Viscosity <a>
 </pre>
 </pre>
 
@@ -361,11 +359,6 @@ with the first error estimate calculated.
 </nobr><br>
 The density property for a solid.
 <br>
-<strong>&lt;Solid_viscosity&gt;</strong> <i>real</i> [0.0] <nobr>
-<strong>&lt;/Solid_viscosity&gt;</strong>
-</nobr><br>
-The viscosity property for a solid.
-<br>
 <strong>&lt;Source_term&gt;</strong> <i>real</i> [0.0] <nobr>
 <strong>&lt;/Source_term&gt;</strong>
 </nobr><br>
diff --git a/documentation/svfsiplus/solver-input-file/equation_parameters/readme.md b/documentation/svfsiplus/solver-input-file/equation_parameters/readme.md
index b24dc13..73dbe83 100755
--- a/documentation/svfsiplus/solver-input-file/equation_parameters/readme.md
+++ b/documentation/svfsiplus/solver-input-file/equation_parameters/readme.md
@@ -119,7 +119,7 @@ If <i>true</i> then use a Taylor-Hood element pair for increased stability.
 
 <h4 id="viscosity_parameters"> Viscosity Subsection </h4>
 The <i>Viscosity Subsection</i> of the <i>Equation Section</i> or <i>Domain Subsection</i> defines 
-the parameters for the viscosity model used by fluid and stokes equations. 
+the parameters for the fluid viscosity model used by fluid, CMM, and stokes equations, or the solid viscosity model used by struct and ustruct.
 
 The <i>Viscosity Subsection</i> is organized as follows
 <div style="background-color: #F0F0F0; padding: 10px; border: 1px solid #d0d0d0; border-left: 1px solid #d0d0d0">
@@ -132,7 +132,7 @@ The <i>Viscosity Subsection</i> is organized as follows
 
 The <strong>Viscosity</strong> keyword defines a subsection for viscosity parameters.
 
-The value of <i>viscosity_model</i> can be
+For fluid, CMM, and stokes equations, the value of <i>viscosity_model</i> can be
 
 <ul style="list-style-type:disc;">
  <li> "newtonian" - Newtonian viscosity model </li>
@@ -212,3 +212,38 @@ The value of the yield stress parameter.
 &lt;<strong>/Viscosity</strong>&gt;
 </div>
 
+For struct and ustruct equations, the value of <i>viscosity_model</i> can be
+
+<ul style="list-style-type:disc;">
+ <li> "Newtonian" - Newtonian viscosity model </li>
+ <li> "Potential" - Pseudo-potential viscosity model </li>
+</ul>
+
+<!-- ---------- Newtonian ---------- -->
+
+<h5> Newtonian </h5>
+<div class="bc_param_div">
+&lt;<strong>Viscosity</strong> model="Newtonian"&gt;
+<br>
+<strong>&lt;Value&gt;</strong> <i>real</i> <nobr>
+<strong>&lt;/Value&gt;</strong>
+</nobr><br>
+The value of the viscosity constant. 
+<br>
+&lt;<strong>/Viscosity</strong>&gt;
+</div>
+
+<!-- ---------- Potential ---------- -->
+
+<h5> Potential </h5>
+<div class="bc_param_div">
+&lt;<strong>Viscosity</strong> model="Potential"&gt;
+<br>
+<strong>&lt;Value&gt;</strong> <i>real</i> <nobr>
+<strong>&lt;/Value&gt;</strong>
+</nobr><br>
+The value of the viscosity constant. 
+<br>
+&lt;<strong>/Viscosity</strong>&gt;
+</div>
+