Updated the docs

Writerside/hi.tree

@@ -22,5 +22,11 @@
             <toc-element topic="Van-der-Waals-attraction.md"/>
             <toc-element topic="Frictional-contact.md"/>
         </toc-element>
+        <toc-element topic="Unary-force-models.md">
+            <toc-element topic="Triangular-facet.md">
+                <toc-element topic="Van-der-Waals-attraction-surface.md"/>
+                <toc-element topic="Frictional-contact-surface.md"/>
+            </toc-element>
+        </toc-element>
     </toc-element>
 </instance-profile>

Writerside/topics/Binary-force-container.md

@@ -3,7 +3,7 @@
 <tldr>
 <p>A record type that stores a variable number of references to binary force model
 instances</p>
-<p>Name: <code>binary_force_container_t</code></p>
+<p>Name: <code>binary_force_container</code></p>
 <p>Defined in: <code>&lt;libgran/granular_system/granular_system.h&gt;</code></p>
 </tldr>
 

Writerside/topics/Binary-force-models.md

@@ -1,6 +1,6 @@
 # Binary force models
 
-libran comes with some build-in binary force models. Here, we provide class fererences
+libran comes with some build-in binary force models. Here, we provide class references
 for reach built-in binary model template:
 
 - [Van der Waals attraction](Van-der-Waals-attraction.md) - simulates Van der Waals attraction

Writerside/topics/Class-reference.md

@@ -12,12 +12,21 @@ arguments, and member functions of objects provided in libgran:
 [`unary_force_container.t`](Unary-force-container.md)
 : A record type that stores references to unary force model instances
 
-[`hamaker_funcor`](Van-der-Waals-attraction.md)
-: A force model that simulates Van der Waals attraction
+[`hamaker_functor`](Van-der-Waals-attraction.md)
+: A force model that simulates Van der Waals attraction between two particles
 
 [`contact_force_functor`](Frictional-contact.md)
 : A force model that simulates frictional forces between contacting particles
 
+[`triangular_facet`](Triangular-facet.md)
+: A wrapper for particle-surface force models
+
+[`surface_hamaker_functor`](Van-der-Waals-attraction-surface.md)
+: A force model that simulates Van der Waals attraction between a particle and a surface
+
+[`surface_contact_force_functor`](Frictional-contact-surface.md)
+: A force model that simulates frictional forces between a particle and a plane in contact
+
 <seealso>
 <category ref="related">
    <a href="Overview.md">Overview</a>

Writerside/topics/Frictional-contact-surface.md

@@ -0,0 +1,135 @@
+# Frictional contact (surface)
+
+<tldr>
+<p>A surface force model that simulates frictional forces between a particle and a plane in contact</p>
+<p>Name: <code>surface_contact_force_functor</code></p>
+<p>Defined in: <code>&lt;libgran/contact_force/surface_contact_force.h&gt;</code></p>
+</tldr>
+
+## Template parameters
+
+{type="wide"}
+`field_value_t`
+: primary field type
+
+`real_t`
+: scalar field type
+
+## Constructor arguments
+
+{type="wide"}
+`size_t n_part`
+: number of particles in the system
+
+`real_t k`
+: normal stiffness
+
+`real_t gamma_n`
+: normal damping coefficient
+
+`real_t k_t`
+: tangential stiffness
+
+`real_t gamma_t`
+: tangential damping coefficient
+
+`real_t mu_s`
+: static friction coefficient for sticking/sliding
+
+`real_t phi_d`
+: dynamic-to-static friction ratio for sticking/sliding
+
+`real_t k_r`
+: rolling resistance stiffness
+
+`real_t gamma_r`
+: rolling resistance damping coefficient
+
+`real_t mu_r`
+: static friction coefficient for rolling resistance
+
+`real_t phi_r`
+: dynamic-to-static friction ratio for rolling resistance
+
+`real_t k_o`
+: torsion resistance stiffness
+
+`real_t gamma_o`
+: torsion resistance damping coefficient
+
+`real_t mu_o`
+: static friction coefficient for torsion resistance
+
+`real_t phi_o`
+: dynamic-to-static friction ratio for torsion resistance
+
+`real_t r_part`
+: particle radius
+
+`real_t mass`
+: particle mass
+
+`real_t inertia`
+: particle moment of inertia
+
+`real_t dt`
+: integration time step
+
+`field_value_t field_zero`
+: zero-valued primary field
+
+`real_t real_zero`
+: zero-valued scalar field
+
+## Public member functions
+
+### operator ()
+
+Synopsis:
+
+Called by the [triangular facet](Triangular-facet.md) to compute the acceleration
+of particle i due to its frictional contact with the triangular facet
+
+Arguments:
+
+{type="wide"}
+`size_t i`
+: index of the particle that is being accelerated
+
+`field_value_t const & x_facet`
+: point on the facet closest to the center of particle i
+
+`std::vector<fielv_value_t> const & x`
+: const reference to the position buffer
+
+`std::vector<fielv_value_t> const & v`
+: const reference to the velocity buffer
+
+`std::vector<fielv_value_t> const & theta`
+: const reference to the orientation buffer
+
+`std::vector<fielv_value_t> const & omega`
+: const reference to the angular velocity buffer
+
+`real_t t`
+: simulation time
+
+Return value:
+
+{type="wide"}
+`std::pair<field_value_t, field_value_t>`
+: translational acceleration and angular acceleration of particle i due to its
+frictional contact with particle j
+
+<seealso>
+<category ref="related">
+   <a href="Overview.md">Overview</a>
+    <a href="Installation.md">Installation</a>
+    <a href="Tutorials.md">Tutorials</a>
+    <a href="Class-reference.md">Class reference</a>
+</category>
+<category ref="external">
+    <a href="https://github.com/egor-demidov/libgran">libgran on GitHub</a>
+    <a href="https://github.com/egor-demidov/libtimestep">libtimestep on GitHub</a>
+</category>
+</seealso>

Writerside/topics/Triangular-facet.md

@@ -0,0 +1,140 @@
+# Triangular facet
+
+<tldr>
+<p>A type that stores a variable number of references to surface force models</p>
+<p>Name: <code>triangular_facet</code></p>
+<p>Defined in: <code>&lt;libgran/surface_force/triangular_facet.h&gt;</code></p>
+</tldr>
+
+## Template parameters
+
+{type="wide"}
+`field_value_t`
+: primary field type
+
+`real_t`
+: scalar field type
+
+`surface_force_functors_t ...`
+: list of surface force model types
+
+## Constructor arguments
+
+{type="wide"}
+`field_value_t v_facet`
+: initial translational velocity of the facet
+
+`std::tuple<field_value_t, field_value_t, field_value_t> vertices`
+: vertices of the triangular facet
+
+`surface_force_functors_t & ...`
+: list of surface force model references
+
+## Public member functions
+
+### operator ()
+
+Synopsis:
+
+Called by the [unary force container](Unary-force-container.md) to compute the acceleration of particle i due to
+surface forces exerted on it because of the triangular facet
+
+Arguments:
+
+{type="wide"}
+`size_t i`
+: index of the particle that is being accelerated
+
+`std::vector<fielv_value_t> const & x`
+: const reference to the position buffer
+
+`std::vector<fielv_value_t> const & v`
+: const reference to the velocity buffer
+
+`std::vector<fielv_value_t> const & theta`
+: const reference to the orientation buffer
+
+`std::vector<fielv_value_t> const & omega`
+: const reference to the angular velocity buffer
+
+`real_t t`
+: simulation time
+
+Return value:
+
+{type="wide"}
+`std::pair<field_value_t, field_value_t>`
+: translational acceleration and angular acceleration of particle i due to surface forces exerted on it by the
+  triangular facet
+
+### get_unit_normal()
+
+Synopsis:
+
+Returns the normal unit vector of the plane in which the triangular facet lies
+
+Arguments:
+
+{type="wide"}
+`void`
+: no arguments
+
+Return value:
+
+{type="wide"}
+`field_value_t const &`
+: const reference to the normal unit vector of the plane in which the triangular facet lies
+
+### get_vertices()
+
+Synopsis:
+
+Returns the tuple with current positions of the vertices of the triangular facet
+
+Arguments:
+
+{type="wide"}
+`void`
+: no arguments
+
+Return value:
+
+{type="wide"}
+`std::tuple<field_value_t, field_value_t, field_value_t> const &`
+: const reference to the tuple containing the positions of the vertices of the triangular facet
+
+### update_positions() 
+
+Synopsis:
+
+Needs to be called at every integration time step to update the positions of the vertices based on the
+facet velocity, `v_facet`, unless the facet is static
+
+Arguments:
+
+{type="wide"}
+`real_t dt`
+: time step by which the vertex positions need to be advanced
+
+{type="wide"}
+`void`
+: no return value
+
+## Public member variables
+
+{type="wide"}
+`field_value_t v_facet`
+: current translational velocity of the triangular facet
+
+<seealso>
+<category ref="related">
+   <a href="Overview.md">Overview</a>
+    <a href="Installation.md">Installation</a>
+    <a href="Tutorials.md">Tutorials</a>
+    <a href="Class-reference.md">Class reference</a>
+</category>
+<category ref="external">
+    <a href="https://github.com/egor-demidov/libgran">libgran on GitHub</a>
+    <a href="https://github.com/egor-demidov/libtimestep">libtimestep on GitHub</a>
+</category>
+</seealso>

Writerside/topics/Unary-force-container.md

@@ -3,7 +3,7 @@
 <tldr>
 <p>A record type that stores a variable number of references to unary force model
 instances</p>
-<p>Name: <code>unary_force_container_t</code></p>
+<p>Name: <code>unary_force_container</code></p>
 <p>Defined in: <code>&lt;libgran/granular_system/granular_system.h&gt;</code></p>
 </tldr>
 

Writerside/topics/Unary-force-models.md

@@ -0,0 +1,24 @@
+# Unary force models
+
+libran comes with some build-in binary force models. Here, we provide class fererences
+for reach built-in binary model template:
+
+- [Triangular facet](Van-der-Waals-attraction.md) - a wrapper that simulates rigid triangular facets with particle-surface interaction
+  forces described by surface force models:
+  - [Van der Waals attraction](Van-der-Waals-attraction-surface.md) - simulates Van der Waals attraction between a
+    particle and a plane based on [Hamaker theory](https://doi.org/10.1016/S0031-8914(37)80203-7)
+  - [Frictional contact](Frictional-contact-surface.md) - simulates frictional forces between a particle
+    and a plane in contact based on the approach described in [Luding 2008](https://doi.org/10.1007/s10035-008-0099-x)
+
+<seealso>
+<category ref="related">
+   <a href="Overview.md">Overview</a>
+    <a href="Installation.md">Installation</a>
+    <a href="Tutorials.md">Tutorials</a>
+    <a href="Class-reference.md">Class reference</a>
+</category>
+<category ref="external">
+    <a href="https://github.com/egor-demidov/libgran">libgran on GitHub</a>
+    <a href="https://github.com/egor-demidov/libtimestep">libtimestep on GitHub</a>
+</category>
+</seealso>