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8  Interaction analyzes and advanced analyzes

8.1  Fluid-structure interaction

If a solid construction interacts with a fluid, both the solid and fluid can be modeled with the materi equation. Interaction forces between solid and fluid will automatically be generated. If required, a temperature field may be imposed. An example of a input file is given below

...
materi_velocity
materi_stress
condif_temperature
end_initia
...
element_group -ra -from 0 -to 100 -ra 1
element_group -ra -from 101 -to 200 -ra 2
...
type 1 -materi -condif
group_materi_elasti_young 1 ...
group_materi_memory -updated
group_condif_conductivity 3 ...
...
type 2 -materi
group_materi_elasti_compressibility 2 ...
group_materi_viscosity 2 ...
group_materi_memory -updated_without_rotation
group_condif_conductivity 2 ...
...
Elements 0-100 are solids (with temperature) and elements 101-200 are fluids (with temperature).

8.2  Consolidation analysis: ground water flow in deforming solid

The ground water flow equation can be combined with the materi equations. The solid will deform due to the ground water flow pressure gradient and ground water flow pressure will change due to solid volume changes. An example of a input file is given below

...
materi_velocity
materi_stress
groundflow_pressure
end_initia
...
groundflow_density ...
groundflow_phreaticlevel ...
...
type 0 -materi -groundflow
( solid material )
group_materi_elasti_young 0 ...
group_materi_memory -updated
( groundflow )
group_groundflow_capacity 0 ...
...
The stresses as initialized by materi_stress are effective stresses. Internally the program calculates with total stresses (effective stress + total pressure) in the material equilibrium equation. You can obtain the total stresses for postprocessing by means of the post_calcul option.

To account for the gravitational stresses, use a density rsat in the group_materi_density record. Here rsat is the saturated density of the groundwater-soil mixture (mass of soil + water per unit volume of the soil-water mixture). Also specify the gravitation in the force_gravity record and, if required, also the force_gravity_time record to apply the gravitation slowly.

8.3  Heat transport in ground water flow

Heat transport in a ground water flow can be analyzed by combining the convection and diffusion of heat equation with the ground water flow equation. Now the velocity in the convection and diffusion of heat equation is taken from the groundflow velocity field ( bi = vig ) if groundflow_velocity is initialized. An example of a input file is given below

...
groundflow_pressure
groundflow_velocity
condif_temperature
end_initia
...
type 0 -groundflow -condif
group_groundflow_compressibility 0 ...
group_condif_conductivity 0 ...
...
If both materi_velocity and groundflow_velocity are initialized, bi = vi + vig.

8.4  Heat transport in materials

Heat transport in a material can be analyzed by combining the convection and diffusion of heat equation with the materi equations. In this way thermal stresses or heat induced convection can be analyzed. Now the velocity in the convection and diffusion of heat equation is taken from the velocity field ( bi = vi ). An example of a input file is given below

...
materi_velocity
materi_stress
condif_temperature
end_initia
...
type 0 -materi -condif
group_materi_elasti_young 0 ...
group_materi_expansion 0 ...
group_materi_memory 0 -updated
group_condif_conductivity 0 ...
...

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