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 # IRockyParticle Struct Reference

 Last update: 16.07.2025 

`#include <<a class="el" href="rocky__particle__api_8hpp_source.xhtml">rocky_particle_api.hpp</a>>`

## <a id="pub-methods" name="pub-methods"></a>Public Member Functions

ROCKY\_FUNCTIONS [IRockyMaterial](structIRockyMaterial.xhtml) [get\_material](#a39ab5586c7a893cbe156d211a10c5efd) () const ROCKY\_FUNCTIONS double3 [get\_centroid\_position](#ab6a1844166c571196740d7cb3e8331a2) () const ROCKY\_FUNCTIONS double [get\_mass](#a9acf8ddfc5a9c3974e19e616193de571) () const ROCKY\_FUNCTIONS double [get\_original\_mass](#a0239b6fe520fb1bc69196cf4c7c298ac) () const ROCKY\_FUNCTIONS double [get\_size](#a702b4bce44c268065cf9961ea88375c3) () const ROCKY\_FUNCTIONS double [get\_release\_time](#af2ebac6fa5a5f9dbb5c37423ef96c471) () const ROCKY\_FUNCTIONS double [get\_cgm\_scale\_factor](#ad931e6e8afe554323408148c245a537e) () const ROCKY\_FUNCTIONS double [get\_volume](#a9a1df9319687462ce0c43b10e691299f) () const ROCKY\_FUNCTIONS double [get\_solid\_volume](#a0fac38fa13ec5aa6495119247b8aa5d6) () const ROCKY\_FUNCTIONS double [get\_surface\_area](#a2200149822388403dfd42afe5574f1f9) () const ROCKY\_FUNCTIONS double [get\_equivalent\_diameter](#a5951469e0997dab052087895e2ebd95c) () const ROCKY\_FUNCTIONS double [get\_sphericity](#ad60e62be9c1084b624f690d94ce0474b) () const ROCKY\_FUNCTIONS double3 [get\_translational\_velocity](#a38420bd69fec1d3a803cbc5d79ea0197) () const ROCKY\_FUNCTIONS double3 [get\_rotational\_velocity](#a1520d3fc8a40e54ad4c47ddb428fddff) () const ROCKY\_FUNCTIONS double [get\_impact\_energy](#a35881133856b678e30b00dfa1c604b96) () const ROCKY\_FUNCTIONS double [get\_strength](#a3479e29c70b861ee7724b3dec473f126) () const ROCKY\_FUNCTIONS double3 [get\_gravity](#a42a986a1659cf8a4374bf43ef6a53f63) () const ROCKY\_FUNCTIONS int [get\_particle\_group\_index](#a063a7d183c621dfffd7fdd644635e51a) () const ROCKY\_FUNCTIONS int [get\_material\_index](#a42f25fc898697efc23ee5576b936efa4) () const ROCKY\_FUNCTIONS double [get\_rolling\_resistance\_coefficient](#ad9ba593e2adb58a8273b23214b14b60b) () const ROCKY\_FUNCTIONS thrust::tuple&lt; double3, double &gt; [get\_orientation\_axis\_angle](#adf12c219fb518212af2932b99c39ae52) () const ROCKY\_FUNCTIONS double4 [get\_orientation\_quaternion](#afd3262f90c7304197e8915b4d40a58f6) () const ROCKY\_FUNCTIONS double3 [get\_resultant\_force](#ac520e2ca9342f42a1260d42bb1f882a0) () const ROCKY\_FUNCTIONS double3 [get\_resultant\_moment](#a58a9a71f0e2cd25a475c5681682a8c7e) () const ROCKY\_FUNCTIONS double [get\_thermal\_conductivity](#a8c3db18d0afb4ebe6d4654d833d904cb) () const ROCKY\_FUNCTIONS void [set\_thermal\_conductivity](#a876773eeef5269e1335ae8a43cbb2d97) (double value) ROCKY\_FUNCTIONS double [get\_poisson\_ratio](#a6d11bc8367e406b7a56f98d92871f059) () const ROCKY\_FUNCTIONS void [set\_poisson\_ratio](#a7225418a496fdaae3dc3ba7bc3d7ebca) (double value) ROCKY\_FUNCTIONS double [get\_specific\_heat](#a5007ecaea7e26cfe50579a959ba91c07) () const ROCKY\_FUNCTIONS int [get\_tag](#a2949c9bf228226090d1e7cf95b63c38f) () const ROCKY\_FUNCTIONS void [set\_specific\_heat](#a6ea5a3cc6356d1b80b3e8cde1fe43211) (double value) ROCKY\_FUNCTIONS [IRockyParticleScalars](structIRockyParticleScalars.xhtml) [get\_scalars](#a305fe472ba945e793d450053dc3b092f) () ROCKY\_FUNCTIONS const [IRockyParticleScalars](structIRockyParticleScalars.xhtml) [get\_scalars](#a0899498770cbebb4b538cbc736e82231) () const ROCKY\_FUNCTIONS [IRockyParticleTransferScalars](structIRockyParticleTransferScalars.xhtml) [get\_transfer\_scalars](#af1bcfda3336619839953a01fbe7828ea) () ROCKY\_FUNCTIONS [IRockyParticleBreakageScalars](structIRockyParticleBreakageScalars.xhtml) [get\_breakage\_scalars](#a9efea10efd70526b3ffe3f723253e44e) () ROCKY\_FUNCTIONS void [remove](#a2fdb4c9362bd6b650aba18ad2fb6c66d) () ROCKY\_FUNCTIONS void [add\_force](#aebc83f532d4bd643046c1c8a93e09f1d) (const double3 &amp;force) ROCKY\_FUNCTIONS void [add\_moment](#a8bb789078434998231949cc5c7c5f3b4) (const double3 &amp;moment) ROCKY\_FUNCTIONS void [set\_frozen](#ae6c885d84af14576949205c3b9fb5bd5) (bool frozen) ROCKY\_FUNCTIONS void [disable\_related\_particle\_contacts](#a98c502d7e6af16bbefdb1ff769810980) () ROCKY\_FUNCTIONS void [enable\_related\_particle\_contacts](#a964a3f27bd8217bbff4301539ecbc1fc) () ROCKY\_FUNCTIONS void [disable\_related\_triangle\_contacts](#a1c445981cc6ac5392560d863927b4211) () ROCKY\_FUNCTIONS void [enable\_related\_triangle\_contacts](#a6d87618d43d29b5d2dcd7f5946e1d0f4) () ROCKY\_FUNCTIONS const double3 [get\_moment\_of\_inertia](#a0ddf76406051617c1cf3ad5602230e74) () const ROCKY\_FUNCTIONS bool [is\_element](#a0ede768e89206dcba2b8929eefa961e7) () const ROCKY\_FUNCTIONS bool [is\_assembly](#a7324f759e40ff9147728dd7e666f9816) () const ROCKY\_FUNCTIONS size\_t [get\_number\_of\_assembly\_parts](#a7174efcf1264a05c6bd5cabe2e927148) () const ROCKY\_FUNCTIONS [IRockyMaterial](structIRockyMaterial.xhtml) [get\_assembly\_part\_material](#a1a737fd34952d960d93f4f8940fd804e) (size\_t part\_id) const ROCKY\_FUNCTIONS void [remove\_from\_contacts\_search](#af4d25f3ada35c955fd0fe7ba24a244c4) () ROCKY\_FUNCTIONS void [add\_to\_contacts\_search](#afe35f545701281de61b805237f4c5d8f) () <a id="details" name="details"></a>## Detailed Description

`<a class="el" href="structIRockyParticle.xhtml">IRockyParticle</a>` is an interface for the internal particle object in Rocky. A particle object is the code representation of an individual particle in a Rocky simulation. It has several access methods to particle-related properties, as well as *particle scalars*, which are special variables that store values per particle that are preserved between time iterations. Values of *particle scalars* can be displayed in a 3D window as any other built-in particle property in Rocky. All property and variable values made available through `<a class="el" href="structIRockyParticle.xhtml">IRockyParticle</a>` are dimensionless.



## Member Function Documentation

<a id="aebc83f532d4bd643046c1c8a93e09f1d" name="aebc83f532d4bd643046c1c8a93e09f1d"></a>## [◆ ](#aebc83f532d4bd643046c1c8a93e09f1d)add\_force()

 ROCKY\_FUNCTIONS void IRockyParticle::add\_force  ( const double3 &amp; *force*) 

This method sums a custom calculated force to the contact and body forcesacting on the particle.Parameters forceThe custom force vector in Cartesian coordinates. 



<a id="a8bb789078434998231949cc5c7c5f3b4" name="a8bb789078434998231949cc5c7c5f3b4"></a>## [◆ ](#a8bb789078434998231949cc5c7c5f3b4)add\_moment()

 ROCKY\_FUNCTIONS void IRockyParticle::add\_moment  ( const double3 &amp; *moment*) 

This method sums a custom calculated moment to the momentsacting on the particle.Parameters momentThe custom moment vector in Cartesian coordinates. 



<a id="afe35f545701281de61b805237f4c5d8f" name="afe35f545701281de61b805237f4c5d8f"></a>## [◆ ](#afe35f545701281de61b805237f4c5d8f)add\_to\_contacts\_search()

 ROCKY\_FUNCTIONS void IRockyParticle::add\_to\_contacts\_search  ( ) 

This method enables the detection of all contacts for the particle.



<a id="a98c502d7e6af16bbefdb1ff769810980" name="a98c502d7e6af16bbefdb1ff769810980"></a>## [◆ ](#a98c502d7e6af16bbefdb1ff769810980)disable\_related\_particle\_contacts()

 ROCKY\_FUNCTIONS void IRockyParticle::disable\_related\_particle\_contacts  ( ) 

This method activates the conditional disabling of particle-to-particle contacts detection.A given particle-to-particle contact will be ignored during the detection stage only if this method has been applied to both particles. 



<a id="a1c445981cc6ac5392560d863927b4211" name="a1c445981cc6ac5392560d863927b4211"></a>## [◆ ](#a1c445981cc6ac5392560d863927b4211)disable\_related\_triangle\_contacts()

 ROCKY\_FUNCTIONS void IRockyParticle::disable\_related\_triangle\_contacts  ( ) 

This method disables the detection of particle-to-triangle contacts for the particle.



<a id="a964a3f27bd8217bbff4301539ecbc1fc" name="a964a3f27bd8217bbff4301539ecbc1fc"></a>## [◆ ](#a964a3f27bd8217bbff4301539ecbc1fc)enable\_related\_particle\_contacts()

 ROCKY\_FUNCTIONS void IRockyParticle::enable\_related\_particle\_contacts  ( ) 

This method deactivates the conditional disabling of particle-to-particle contact detection,previously activated using the `<a class="el" href="#a98c502d7e6af16bbefdb1ff769810980">IRockyParticle::disable_related_particle_contacts</a>` 



<a id="a6d87618d43d29b5d2dcd7f5946e1d0f4" name="a6d87618d43d29b5d2dcd7f5946e1d0f4"></a>## [◆ ](#a6d87618d43d29b5d2dcd7f5946e1d0f4)enable\_related\_triangle\_contacts()

 ROCKY\_FUNCTIONS void IRockyParticle::enable\_related\_triangle\_contacts  ( ) 

This method enables the detection of particle-to-triangle contacts for the particle.



<a id="a1a737fd34952d960d93f4f8940fd804e" name="a1a737fd34952d960d93f4f8940fd804e"></a>## [◆ ](#a1a737fd34952d960d93f4f8940fd804e)get\_assembly\_part\_material()

 ROCKY\_FUNCTIONS [IRockyMaterial](structIRockyMaterial.xhtml) IRockyParticle::get\_assembly\_part\_material  ( size\_t *part\_id*)  const

Parameters part\_idThe index of an assembly part. ReturnsAn `<a class="el" href="structIRockyMaterial.xhtml">IRockyMaterial</a>` object that gives access to the values of physical properties associated to the material from which the assembly part referent to `part_id` is made. 



<a id="a9efea10efd70526b3ffe3f723253e44e" name="a9efea10efd70526b3ffe3f723253e44e"></a>## [◆ ](#a9efea10efd70526b3ffe3f723253e44e)get\_breakage\_scalars()

 ROCKY\_FUNCTIONS [IRockyParticleBreakageScalars](structIRockyParticleBreakageScalars.xhtml) IRockyParticle::get\_breakage\_scalars  ( ) 

ReturnsAn `<a class="el" href="structIRockyParticleBreakageScalars.xhtml">IRockyParticleBreakageScalars</a>` object, that gives access to all particle breakage scalars variables defined in the project. 



<a id="ab6a1844166c571196740d7cb3e8331a2" name="ab6a1844166c571196740d7cb3e8331a2"></a>## [◆ ](#ab6a1844166c571196740d7cb3e8331a2)get\_centroid\_position()

 ROCKY\_FUNCTIONS double3 IRockyParticle::get\_centroid\_position  ( )  const

ReturnsThe Cartesian coordinates of the current position of the particle's centroid. 



<a id="ad931e6e8afe554323408148c245a537e" name="ad931e6e8afe554323408148c245a537e"></a>## [◆ ](#ad931e6e8afe554323408148c245a537e)get\_cgm\_scale\_factor()

 ROCKY\_FUNCTIONS double IRockyParticle::get\_cgm\_scale\_factor  ( )  const

ReturnsThe particle's Coarse-grain Modeling (CGM) scale factor. 



<a id="a5951469e0997dab052087895e2ebd95c" name="a5951469e0997dab052087895e2ebd95c"></a>## [◆ ](#a5951469e0997dab052087895e2ebd95c)get\_equivalent\_diameter()

 ROCKY\_FUNCTIONS double IRockyParticle::get\_equivalent\_diameter  ( )  const

ReturnsThe equivalent diameter of the particle, which is defined as the diameter of a sphere of volume equal to the particle's volume. 



<a id="a42a986a1659cf8a4374bf43ef6a53f63" name="a42a986a1659cf8a4374bf43ef6a53f63"></a>## [◆ ](#a42a986a1659cf8a4374bf43ef6a53f63)get\_gravity()

 ROCKY\_FUNCTIONS double3 IRockyParticle::get\_gravity  ( )  const

ReturnsThe gravitational acceleration vector in Cartesian coordinates. 



<a id="a35881133856b678e30b00dfa1c604b96" name="a35881133856b678e30b00dfa1c604b96"></a>## [◆ ](#a35881133856b678e30b00dfa1c604b96)get\_impact\_energy()

 ROCKY\_FUNCTIONS double IRockyParticle::get\_impact\_energy  ( )  const

ReturnsThe sum of the impact energy registered in all active contacts on the surface of the particle until the current time.AttentionThis value will be available only if an instantaneous breakage model is enabled in the simulation. 



<a id="a9acf8ddfc5a9c3974e19e616193de571" name="a9acf8ddfc5a9c3974e19e616193de571"></a>## [◆ ](#a9acf8ddfc5a9c3974e19e616193de571)get\_mass()

 ROCKY\_FUNCTIONS double IRockyParticle::get\_mass  ( )  const

ReturnsThe current value of the particle's mass. This value will be different from the original particle's mass only if the mass increment particle scalar is enabled in the simulation. 



<a id="a39ab5586c7a893cbe156d211a10c5efd" name="a39ab5586c7a893cbe156d211a10c5efd"></a>## [◆ ](#a39ab5586c7a893cbe156d211a10c5efd)get\_material()

 ROCKY\_FUNCTIONS [IRockyMaterial](structIRockyMaterial.xhtml) IRockyParticle::get\_material  ( )  const

ReturnsAn `<a class="el" href="structIRockyMaterial.xhtml">IRockyMaterial</a>` object that gives access to the values of physical properties associated to the material from which the particle is made.AttentionInvoking this method on assembly particles results on undefined behavior, as assembly particles may have multiple materials. Prefer to use `<a class="el" href="#a1a737fd34952d960d93f4f8940fd804e">IRockyParticle::get_assembly_part_material</a>` instead. 



<a id="a42f25fc898697efc23ee5576b936efa4" name="a42f25fc898697efc23ee5576b936efa4"></a>## [◆ ](#a42f25fc898697efc23ee5576b936efa4)get\_material\_index()

 ROCKY\_FUNCTIONS int IRockyParticle::get\_material\_index  ( )  const

ReturnsThe material index associated to that particle 



<a id="a0ddf76406051617c1cf3ad5602230e74" name="a0ddf76406051617c1cf3ad5602230e74"></a>## [◆ ](#a0ddf76406051617c1cf3ad5602230e74)get\_moment\_of\_inertia()

 ROCKY\_FUNCTIONS const double3 IRockyParticle::get\_moment\_of\_inertia  ( )  const

ReturnsA 3D vector whose components are the principal values of the particle's moment of inertia tensor. 



<a id="a7174efcf1264a05c6bd5cabe2e927148" name="a7174efcf1264a05c6bd5cabe2e927148"></a>## [◆ ](#a7174efcf1264a05c6bd5cabe2e927148)get\_number\_of\_assembly\_parts()

 ROCKY\_FUNCTIONS size\_t IRockyParticle::get\_number\_of\_assembly\_parts  ( )  const

ReturnsThe number of parts that compose the assembly. 



<a id="adf12c219fb518212af2932b99c39ae52" name="adf12c219fb518212af2932b99c39ae52"></a>## [◆ ](#adf12c219fb518212af2932b99c39ae52)get\_orientation\_axis\_angle()

 ROCKY\_FUNCTIONS thrust::tuple&lt; double3, double &gt; IRockyParticle::get\_orientation\_axis\_angle  ( )  const

ReturnsA tuple whose two components define the axis-angle particle orientation. The first one is a three dimensional vector representing the orientation axis, the second one is a single value representing the angle. 



<a id="afd3262f90c7304197e8915b4d40a58f6" name="afd3262f90c7304197e8915b4d40a58f6"></a>## [◆ ](#afd3262f90c7304197e8915b4d40a58f6)get\_orientation\_quaternion()

 ROCKY\_FUNCTIONS double4 IRockyParticle::get\_orientation\_quaternion  ( )  const

ReturnsThe quaternion that represents the particle's orientation, expressed as a four-dimensional array \\((q\_r, q\_i, q\_j, q\_k)\\). 



<a id="a0239b6fe520fb1bc69196cf4c7c298ac" name="a0239b6fe520fb1bc69196cf4c7c298ac"></a>## [◆ ](#a0239b6fe520fb1bc69196cf4c7c298ac)get\_original\_mass()

 ROCKY\_FUNCTIONS double IRockyParticle::get\_original\_mass  ( )  const

ReturnsThe original value of the mass of a particle when it enters into the simulation. 



<a id="a063a7d183c621dfffd7fdd644635e51a" name="a063a7d183c621dfffd7fdd644635e51a"></a>## [◆ ](#a063a7d183c621dfffd7fdd644635e51a)get\_particle\_group\_index()

 ROCKY\_FUNCTIONS int IRockyParticle::get\_particle\_group\_index  ( )  const

ReturnsThe index that uniquely identifies the particle group to which the particle belongs. 



<a id="a6d11bc8367e406b7a56f98d92871f059" name="a6d11bc8367e406b7a56f98d92871f059"></a>## [◆ ](#a6d11bc8367e406b7a56f98d92871f059)get\_poisson\_ratio()

 ROCKY\_FUNCTIONS double IRockyParticle::get\_poisson\_ratio  ( )  const

ReturnsThe particle's Poisson's ratio value. If this property was defined as variable in the module's specification file, the method will return the value specifically assigned to the particle. Otherwise, it will return the value specified in the Rocky UI for the particle's associated material. 



<a id="af2ebac6fa5a5f9dbb5c37423ef96c471" name="af2ebac6fa5a5f9dbb5c37423ef96c471"></a>## [◆ ](#af2ebac6fa5a5f9dbb5c37423ef96c471)get\_release\_time()

 ROCKY\_FUNCTIONS double IRockyParticle::get\_release\_time  ( )  const

ReturnsThe time at which the particle was released. 



<a id="ac520e2ca9342f42a1260d42bb1f882a0" name="ac520e2ca9342f42a1260d42bb1f882a0"></a>## [◆ ](#ac520e2ca9342f42a1260d42bb1f882a0)get\_resultant\_force()

 ROCKY\_FUNCTIONS double3 IRockyParticle::get\_resultant\_force  ( )  const

ReturnsThe resultant force vector acting on the particle, in Cartesian coordinates. This force is a combination of the forces calculated during the current time iteration that are applied on the particle, including contact forces, joint forces, fluid forces, and other forces coming from custom modules. If this method is called before the force calculation stage it will return a zero vector.AttentionThe force of gravity acting on the particle is not included in this resultant force. 



<a id="a58a9a71f0e2cd25a475c5681682a8c7e" name="a58a9a71f0e2cd25a475c5681682a8c7e"></a>## [◆ ](#a58a9a71f0e2cd25a475c5681682a8c7e)get\_resultant\_moment()

 ROCKY\_FUNCTIONS double3 IRockyParticle::get\_resultant\_moment  ( )  const

ReturnsThe resultant moment vector applied to the particle, in Cartesian coordinates. The resultant moment is the combination of all moments caused by the forces acting upon the particle, including contact forces, joint forces, fluid forces, and other forces coming from custom modules. If this method is called before the force calculation stage it will return a zero vector. 



<a id="ad9ba593e2adb58a8273b23214b14b60b" name="ad9ba593e2adb58a8273b23214b14b60b"></a>## [◆ ](#ad9ba593e2adb58a8273b23214b14b60b)get\_rolling\_resistance\_coefficient()

 ROCKY\_FUNCTIONS double IRockyParticle::get\_rolling\_resistance\_coefficient  ( )  const

ReturnsThe particle's rolling resistance coefficient 



<a id="a1520d3fc8a40e54ad4c47ddb428fddff" name="a1520d3fc8a40e54ad4c47ddb428fddff"></a>## [◆ ](#a1520d3fc8a40e54ad4c47ddb428fddff)get\_rotational\_velocity()

 ROCKY\_FUNCTIONS double3 IRockyParticle::get\_rotational\_velocity  ( )  const

ReturnsThe current particle's rotational velocity vector expressed in Cartesian coordinates. 



<a id="a305fe472ba945e793d450053dc3b092f" name="a305fe472ba945e793d450053dc3b092f"></a>## [◆ ](#a305fe472ba945e793d450053dc3b092f)get\_scalars() \[1/2\]

 ROCKY\_FUNCTIONS [IRockyParticleScalars](structIRockyParticleScalars.xhtml) IRockyParticle::get\_scalars  ( ) 

ReturnsAn `<a class="el" href="structIRockyParticleScalars.xhtml">IRockyParticleScalars</a>` object, that gives access to all particle scalars variables defined in the project. 



<a id="a0899498770cbebb4b538cbc736e82231" name="a0899498770cbebb4b538cbc736e82231"></a>## [◆ ](#a0899498770cbebb4b538cbc736e82231)get\_scalars() \[2/2\]

 ROCKY\_FUNCTIONS const [IRockyParticleScalars](structIRockyParticleScalars.xhtml) IRockyParticle::get\_scalars  ( )  const

ReturnsA const `<a class="el" href="structIRockyParticleScalars.xhtml">IRockyParticleScalars</a>` object, that gives access to all particle scalars variables defined in the project. 



<a id="a702b4bce44c268065cf9961ea88375c3" name="a702b4bce44c268065cf9961ea88375c3"></a>## [◆ ](#a702b4bce44c268065cf9961ea88375c3)get\_size()

 ROCKY\_FUNCTIONS double IRockyParticle::get\_size  ( )  const

ReturnsThe current value of the particle's size. 



<a id="a0fac38fa13ec5aa6495119247b8aa5d6" name="a0fac38fa13ec5aa6495119247b8aa5d6"></a>## [◆ ](#a0fac38fa13ec5aa6495119247b8aa5d6)get\_solid\_volume()

 ROCKY\_FUNCTIONS double IRockyParticle::get\_solid\_volume  ( )  const

ReturnsThe current value of the particle's solid volume. If the particle is porous (porosity &gt; 0), the solid volume is the volume of the solid matrix. Otherwise, the volume returned by this function will coincide with the one returned by the `get_volume` function. 



<a id="a5007ecaea7e26cfe50579a959ba91c07" name="a5007ecaea7e26cfe50579a959ba91c07"></a>## [◆ ](#a5007ecaea7e26cfe50579a959ba91c07)get\_specific\_heat()

 ROCKY\_FUNCTIONS double IRockyParticle::get\_specific\_heat  ( )  const

ReturnsThe particle's specific heat value. If this property was defined as variable in the module's specification file, the method will return the value specifically assigned to the particle. Otherwise, it will return the value specified in the Rocky UI for the particle's associated material. 



<a id="ad60e62be9c1084b624f690d94ce0474b" name="ad60e62be9c1084b624f690d94ce0474b"></a>## [◆ ](#ad60e62be9c1084b624f690d94ce0474b)get\_sphericity()

 ROCKY\_FUNCTIONS double IRockyParticle::get\_sphericity  ( )  const

ReturnsThe particle's sphericity value, which is defined as the ratio of \\(A\_s\\) to \\(A\_p\\), where \\(A\_s\\) is the surface area of a sphere with the same volume as the particle, whereas \\(A\_p\\) is the surface area of the particle itself. In general terms, the sphericity measures how closely the particle's actual shape resembles the shape of a perfect sphere. 



<a id="a3479e29c70b861ee7724b3dec473f126" name="a3479e29c70b861ee7724b3dec473f126"></a>## [◆ ](#a3479e29c70b861ee7724b3dec473f126)get\_strength()

 ROCKY\_FUNCTIONS double IRockyParticle::get\_strength  ( )  const

ReturnsA random value between 0 and 1 assigned to a particle at the time of generation. This value can be related to the breakage probability in a custom instantaneous breakage model. 



<a id="a2200149822388403dfd42afe5574f1f9" name="a2200149822388403dfd42afe5574f1f9"></a>## [◆ ](#a2200149822388403dfd42afe5574f1f9)get\_surface\_area()

 ROCKY\_FUNCTIONS double IRockyParticle::get\_surface\_area  ( )  const

ReturnsThe current value of the particle's surface area. 



<a id="a2949c9bf228226090d1e7cf95b63c38f" name="a2949c9bf228226090d1e7cf95b63c38f"></a>## [◆ ](#a2949c9bf228226090d1e7cf95b63c38f)get\_tag()

 ROCKY\_FUNCTIONS int IRockyParticle::get\_tag  ( )  const

ReturnsThe tag value inherited from the tags assigned to the segments of a custom fiber, if the `<a class="el" href="structIRockyParticle.xhtml">IRockyParticle</a>` object represents an element of a custom fiber. The values of those tags must be specified in the column labeled "tag" in the csv file that defines the geometry of a custom fiber. All elements that arise from the subdivision of a given segment inherit the tag value assigned to that segment. If tags are not defined for a custom fiber or if this function is used with particles which are not elements of a custom fiber, this function will return -1. 



<a id="a8c3db18d0afb4ebe6d4654d833d904cb" name="a8c3db18d0afb4ebe6d4654d833d904cb"></a>## [◆ ](#a8c3db18d0afb4ebe6d4654d833d904cb)get\_thermal\_conductivity()

 ROCKY\_FUNCTIONS double IRockyParticle::get\_thermal\_conductivity  ( )  const

ReturnsThe particle's thermal conductivity. If this property was defined as variable in the module's specification file, the method will return the value specifically assigned to the particle. Otherwise, it will return the value specified in the Rocky UI for the particle's associated material. 



<a id="af1bcfda3336619839953a01fbe7828ea" name="af1bcfda3336619839953a01fbe7828ea"></a>## [◆ ](#af1bcfda3336619839953a01fbe7828ea)get\_transfer\_scalars()

 ROCKY\_FUNCTIONS [IRockyParticleTransferScalars](structIRockyParticleTransferScalars.xhtml) IRockyParticle::get\_transfer\_scalars  ( ) 

ReturnsAn `<a class="el" href="structIRockyParticleTransferScalars.xhtml">IRockyParticleTransferScalars</a>` object, that gives access to all particle transfer scalars variables defined in the project. 



<a id="a38420bd69fec1d3a803cbc5d79ea0197" name="a38420bd69fec1d3a803cbc5d79ea0197"></a>## [◆ ](#a38420bd69fec1d3a803cbc5d79ea0197)get\_translational\_velocity()

 ROCKY\_FUNCTIONS double3 IRockyParticle::get\_translational\_velocity  ( )  const

ReturnsThe current particle's translational velocity vector expressed in Cartesian coordinates. 



<a id="a9a1df9319687462ce0c43b10e691299f" name="a9a1df9319687462ce0c43b10e691299f"></a>## [◆ ](#a9a1df9319687462ce0c43b10e691299f)get\_volume()

 ROCKY\_FUNCTIONS double IRockyParticle::get\_volume  ( )  const

ReturnsThe current value of the particle's volume. If the particle is porous (porosity &gt; 0), the volume returned is the particle's total or bulk volume, that is the volume obtained by summing the solid volume and the pore volume. 



<a id="a7324f759e40ff9147728dd7e666f9816" name="a7324f759e40ff9147728dd7e666f9816"></a>## [◆ ](#a7324f759e40ff9147728dd7e666f9816)is\_assembly()

 ROCKY\_FUNCTIONS bool IRockyParticle::is\_assembly  ( )  const

ReturnsTrue if the given particle is an assembly, false otherwise. 



<a id="a0ede768e89206dcba2b8929eefa961e7" name="a0ede768e89206dcba2b8929eefa961e7"></a>## [◆ ](#a0ede768e89206dcba2b8929eefa961e7)is\_element()

 ROCKY\_FUNCTIONS bool IRockyParticle::is\_element  ( )  const

ReturnsTrue if the given particle is an element within a flexible particle, false otherwise. 



<a id="a2fdb4c9362bd6b650aba18ad2fb6c66d" name="a2fdb4c9362bd6b650aba18ad2fb6c66d"></a>## [◆ ](#a2fdb4c9362bd6b650aba18ad2fb6c66d)remove()

 ROCKY\_FUNCTIONS void IRockyParticle::remove  ( ) 

This method removes permanently the particle from the simulation.



<a id="af4d25f3ada35c955fd0fe7ba24a244c4" name="af4d25f3ada35c955fd0fe7ba24a244c4"></a>## [◆ ](#af4d25f3ada35c955fd0fe7ba24a244c4)remove\_from\_contacts\_search()

 ROCKY\_FUNCTIONS void IRockyParticle::remove\_from\_contacts\_search  ( ) 

This method disables the detection of all contacts for the particle.



<a id="ae6c885d84af14576949205c3b9fb5bd5" name="ae6c885d84af14576949205c3b9fb5bd5"></a>## [◆ ](#ae6c885d84af14576949205c3b9fb5bd5)set\_frozen()

 ROCKY\_FUNCTIONS void IRockyParticle::set\_frozen  ( bool *frozen*) 

This method sets the frozen state of a particle. When the frozen state of a particleis set to `true`, the solution of the motion equations for this particle are skipped afterwards.Parameters frozenTrue if the particle should be frozen, false otherwise. 



<a id="a7225418a496fdaae3dc3ba7bc3d7ebca" name="a7225418a496fdaae3dc3ba7bc3d7ebca"></a>## [◆ ](#a7225418a496fdaae3dc3ba7bc3d7ebca)set\_poisson\_ratio()

 ROCKY\_FUNCTIONS void IRockyParticle::set\_poisson\_ratio  ( double *value*) 

This method sets the Poisson's ratio value for the particle. This operation willbe allowed only if Poisson's ratio was defined as a variable property for particles in the module's specification file. Otherwise, a segmentation fault will occur.Parameters valueThe Poisson's ratio to be set. 



<a id="a6ea5a3cc6356d1b80b3e8cde1fe43211" name="a6ea5a3cc6356d1b80b3e8cde1fe43211"></a>## [◆ ](#a6ea5a3cc6356d1b80b3e8cde1fe43211)set\_specific\_heat()

 ROCKY\_FUNCTIONS void IRockyParticle::set\_specific\_heat  ( double *value*) 

This method sets the specific heat value for the particle. This operation willbe allowed only if Poisson's ratio was defined as a variable property for particles in the module's specification file. Otherwise, a segmentation fault will occur.Parameters valueThe specific heat to be set. 



<a id="a876773eeef5269e1335ae8a43cbb2d97" name="a876773eeef5269e1335ae8a43cbb2d97"></a>## [◆ ](#a876773eeef5269e1335ae8a43cbb2d97)set\_thermal\_conductivity()

 ROCKY\_FUNCTIONS void IRockyParticle::set\_thermal\_conductivity  ( double *value*) 

This method sets the thermal conductivity value for the particle. This operation willbe allowed only if thermal conductivity was defined as a variable property for particles in the module's specification file. Otherwise, a segmentation fault will occur.Parameters valueThe thermal conductivity to be set.