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--- doc:user:elements:boundaries:convection [2015/01/26 10:24] – joris
+++ doc:user:elements:boundaries:convection [2026/07/29 18:05] (current) – [Material] papeleux
@@ Line 1: / Line 1: @@
-====== Convection ======
+====== Convection Material ======
+<note important>
+This Documentation refers to Metafor version >= 3593.
+for more informations on changes see [[https://gitlab.uliege.be/am-dept/MN2L/oo_meta/-/merge_requests/167|MR !167]] for technical informations).
-===== Materials=====
+for a Metafor version < 3593, please refers to this [[convection_pre3593|page]].
+</note>
-Since pressure/shear interactions are boundary conditions interactions (''LoadingInteraction''), no materials must be associated to the element.
+The Convection Materials are implemented to take into account the heat exchange by convection between the boundary of a mesh and the surrounding fluid atmosphere. They are designed to be associated with ''Tm(2)Boundary2D(3D)Element'', but will also be usable with ''Tm(2)Source2D(3D)Element'', even if the physical meaning is questioning...
-===== Element =====
+Excepted to the ''ConvectionMaterial'', the flux is linked to a spatial distribution functions related to a set of  local coordinates {$x'$, $y'$, $z'$}, which are handled by the X, Y and Z Axis defined in the Material.
+The local Axis are Line Objects that are defined in the CurveSet and referred in the material by their number.
-Therefore, the first step consist in defining an ''[[doc:user:elements:general:def_element_properties|ElementProperties]]'', as
-  prp = ElementProperties(typeEl)
+{{ doc:user:elements:boundaries:heat_localcoord.png?400 |Coordonnées locales du la source de chaleur}}
-  prp.put(param1, value1)
-  prp.depend(param1, fct1, Lock1)) #optional
-  ...
+The different laws allows to exchange heat with atmosphere or to model heat exchange due to a fluid jet such as a gas torch for example.
+===== Material =====
+Therefore, the first step consist in defining an ''[[doc:user:elements:general:materials|MaterialProperties]]'', as
+  mat = materset.define(no, matType )
+  mat.put(param1, value1)
+  mat.depend(param1, fct1, Lock1)) #optional
 where
-|''typeEl'' | desired element (for example ''Tm[2]Convection[2|3]DElement'')|
+param1	name of the property associated to the element (for example RAY_EMISSIVITY
-|''param1''| name of the property associated to the element (for example ''CONV_COEF''|
+value1	value of the corresponding property
-|''value1''| value of the corresponding property |
+fct1	function which characterises the dependency of the property (optional: no fct if no dependency)
-|''fct1''| function which characterizes the dependency of the property (optional: no fct if no dependency) |
+Lock1	Lock which defines the dependency variable of the property (compulsory if there is a dependency)
-|''Lock1''| [[doc:user:general:locks|Lock]] which defines the dependency variable of the property (compulsory if there is a dependency) |
-==== Tm[2]Convection[2|3]DElement ====
+==== ConvectionMaterial ====
-Convection element in 2/3D, first or second order (thermal field of second order)
+the heat flux is computed by $flux = C (T_{fluid}-T)$
+with :
+  * $C$ : Convection coefficient
+  * $T$ : Temperature at the Integration Point
+  * $T_{fluid}$ : Temperature of the fluid
-<note>TO DO : Ajouter équations de convection </note>
 === Parameters ===
 ^   Name                                          ^     Description       ^  Dependency ^
-| ''STIFFMETHOD'' | Method used to compute the stiffness matrix\\= ''STIFF_ANALYTIC'' : analytic matrix (default)\\ = ''STIFF_NUMERIC''  : numerical matrix |  -  |
+| ''CONV_COEF'' | Convection coefficient |  TM / TO  |
-| ''CONV_COEF''  | Thermal convection  |  time |
+| ''TEMP_FLUIDE''  | Temperature of the fluid |  TM  |
-| ''TEMP_FLUIDE''  | Temperature of the fluid |  time |
-| ''NPG''    | Number of integration points (default : tm : 2 / tm2 : 3)   |  -  |
-===== Interaction =====
-The interaction is defined as:
+==== RectangularHConvectionMaterial ====
-  load = LoadingInteraction(no)
+the heat flux is computed by $flux = C (T_{fluid}-T)$ inside the rectangular box
-  load.push(gObject1)
+and $flux = 0.0$ outside of the rectangular box
-  load.push(gObject2)
-  ...
-  load.addProperty(prp)
-  interactionset.add(load)
-where
+<note important> Add Drawing </note>
-| ''no''       | number of the ''Interaction''  |
-| ''gObject1'', ''gObject2''  | mesh geometric entity where the boundary conditions are applied  |
+The box is defined by its dimension ($kX$ and $kY$) and moving axes X & Z axis (=> Y axis is deducted from X & Z)
-| ''prp''      | [[doc:user:elements:general:def_element_properties|Properties]] of [[#Element|boundary condition elements]] to generate |
+with :
+  * $C$ : Convection coefficient
+  * $T$ : Temperature at the Integration Point
+  * $T_{fluid}$ : Temperature of the fluid
+^   Name                                          ^     Description       ^  Dependency ^
+| ''CONV_COEF'' | Convection coefficient |  TM / TO  |
+| ''TEMP_FLUIDE''  | Temperature of the fluid |  TM  |
+| ''CONV_KX'' | Dimension of the rectangle in the first direction (Aligned on the local X Axis) |  TM  |
+| ''CONV_KY''  | Dimension of the rectangle in the first direction (Aligned on the local Y Axis) |  TM  |
+| ''HEATFLUX_NUM_AX_X'' | Number of the X Axis (Line object  in the CurveSet)  |  -  |
+| ''HEATFLUX_NUM_AX_Z''  | Number of the Z Axis (Line object in the CurveSet) (optional) |  -  |
+==== GaussianHConvectionMaterial ====
+The heat flux is computed by $flux = C exp^{(-(\frac{x_l}{k_x})^2-(\frac{y_l}{k_y})^2)} (T_{fluid}-T)$
+so a Gaussian distribution of the heat flux around moving axis.
+<note important> Add Drawing </note>
+The distribution is defined by its characteristic lengths ($k_x$ and $k_y$) and moving axes X & Z axis (=> Y axis is deducted from X & Z)
+with :
+  * $C$ : Convection coefficient
+  * $x_l$ & $y_l$ : local coordinate in the referential of the Gaussian
+  * $k_x$ & $K_y$ : Characteristic dimension of the Gaussian in its local referential
+  * $T$ : Temperature at the Integration Point
+  * $T_{fluid}$ : temperature of the fluid
+^   Name                                          ^     Description       ^  Dependency ^
+| ''CONV_COEF'' | Convection coefficient |  TM / TO  |
+| ''TEMP_FLUIDE''  | Temperature of the fluid |  TM  |
+| ''CONV_KX'' | Distribution characteristic length in X local direction |  TM  |
+| ''CONV_KY''  | Distribution characteristic length in X local direction |  TM  |
+| ''HEATFLUX_NUM_AX_X'' | Number of the X Axis (Line object  in the CurveSet)  |  -  |
+| ''HEATFLUX_NUM_AX_Z''  | Number of the Z Axis (Line object in the CurveSet) (optional) |  -  |
+| ''HEATFLUX_RESCALE'' | parameter activating the rescale algorithm \\ (to ensure the total heat given by the load is received by the system even with coarse mesh) |  -  |
+==== LogNormHConvectionMaterial ====
+The heat flux is computed by $flux = C exp^{(-(log(\frac{|x_l|}{k_x}+1))^2-(log(\frac{|y_l|}{k_y}+1))^2)} (T_{fluid}-T)$  so a Logarithmic distribution of the heat flux around moving axis.
+<note important> Add Drawing </note>
+The distributionis defined by its  characteristic lengths ($k_x$ and $k_y$) and moving axes X & Z axis (=> Y axis is deducted from X & Z)
+with :
+  * $C$ : Convection coefficient
+  * $x_l$ & $y_l$ : local coordinate in the referential of the normalised logarithmic
+  * $k_x$ & $K_y$ : Characteristic dimension of the normalised logarithmic in its local referential
+  * $T$ : Temperature at the Integration Point
+  * $T_{fluid}$ : temperature of the fluid
+^   Name                                          ^     Description       ^  Dependency ^
+| ''CONV_COEF'' | Convection coefficient |  TM / TO  |
+| ''TEMP_FLUIDE''  | Temperature of the fluid |  TM  |
+| ''CONV_KX'' | Distribution characteristic length in X local direction |  TM  |
+| ''CONV_KY''  | Distribution characteristic length in Y local direction |  TM  |
+| ''HEATFLUX_NUM_AX_X'' | Number of the X Axis (Line object  in the CurveSet)  |  -  |
+| ''HEATFLUX_NUM_AX_Z''  | Number of the Z Axis (Line object in the CurveSet) (optional) |  -  |
+| ''HEATFLUX_RESCALE'' | parameter activating the rescale algorithm \\ (to ensure the total heat given by the load is received by the system even with coarse mesh) |  -  |
+==== CombineHConvectionMaterial ====
+The CombineHConvectionMaterial is implemented to model moving and inclined  gas torch convective heat source.
+The convective coefficient distribution is different according to local X and Y direction. It is also different upstream and down stream. Finally, outside of the gas flux, the heat transfer is driven by a free natural convection.
+The heat flux is computed by $flux = C exp^{(-xpart^2-ypart^2)} (T_{fluid}-T)$  so a distribution of the heat flux around moving axis.
+<note important> Add Drawing </note>
+The distribution is defined by different formulation :
+  * Gaussian : $ xpart = frac{x_l}{k_x}$
+  * LogNorm : $ xpart = log(frac{|x_l|}{k_x}+1)$
+In local X : it can also be different for $x_l > 0$ and $x_l < 0$ to model an inclined gas torch (where upstream and downstream fluid flow is not the same). Distribution type and characteristic dimension can be different up and downstream)
+In local Y direction the distribution can also be Gaussian or LogNorm but is similar up and downstream.
+Further more, if the "Distributed convection coefficient" is lower than a natural convective coefficient :
+$C exp^{(-xpart^2-ypart^2)} < C_{nat}$
+the heatFlux is then computed by natural convection : $flux = C_{nat} (T_{nat fluid}-T)$
+with :
+  * $C$ : Convection coefficient (forced)
+  * $C_{nat}$ : Convection coefficient (Natural)
+  * $x_l$ & $y_l$ : local coordinate in the referential of the normalised logarithmic
+  * $k_x$ & $K_y$ : Characteristic dimension of distribution in its local referential
+  * $xpart$ - $ypart$ : distributed local coefficient
+  * $T$ : Temperature at the Integration Point
+  * $T_{fluid}$ : temperature of the fluid (foced
+  * $T_{nat fluid}$ : temperature of the fluid
+^   Name                                          ^     Description       ^  Dependency ^
+| ''CONV_COEF'' | Convection coefficient |  TM / TO  |
+| ''TEMP_FLUIDE''  | Temperature of the fluid |  TM  |
+| ''CONV_TYPE_XF''  | type of distribution for local upstream X direction (CONV_GAUSSIAN or CONV_LOGNORM)no default |  -  |
+| ''CONV_TYPE_XR''  | type of distribution for local upstream X direction  (CONV_GAUSSIAN or CONV_LOGNORM) no default |  -  |
+| ''CONV_TYPE_Y''   | type of distribution for local Y direction   (CONV_GAUSSIAN or CONV_LOGNORM) no default |  -  |
+| ''CONV_KX'' | Distribution characteristic length in Upstream X local direction |  TM  |
+| ''CONV_KXR'' | Distribution characteristic length in Downstream X local direction |  TM  |
+| ''CONV_KY''  | Distribution characteristic length in Upstream Y local direction |  TM  |
+| ''WITH_NATCONV'' | activate natural convection |  -  |
+| ''CONV_COEFNAT'' | Natural Convection coefficient |  TM / TO  |
+| ''CONV_TEMPNAT''  | Natural Temperature of the fluid |  TM  |
+| ''HEATFLUX_NUM_AX_X'' | Number of the X Axis (Line object  in the CurveSet)  |  -  |
+| ''HEATFLUX_NUM_AX_Z''  | Number of the Z Axis (Line object in the CurveSet) (optional) |  -  |
+| ''HEATFLUX_RESCALE'' | parameter activating the rescale algorithm \\ (to ensure the total heat given by the load is received by the system even with coarse mesh) |  -  |