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# comsol Solid shrinkage

2023-02-28 05:27

The following is an example of fluid-structure coupling, describing the flow of water around a homogeneous solid material(polymer) as it shrinks. In this case, a fluid-structure coupling model is established by linking the linear thermal expansion of polymer with the Navier-Stokes equations. Simulation under different conditions can be carried out by modifying model parameters and material properties.

The specific steps are as follows:

Create 3D model
Create 3D model in COMSOL, including polymer solid and surrounding water flow.

Define the physical fields and boundary conditions
Define the physical fields of heat conduction, solid mechanics and fluid dynamics and set the corresponding boundary conditions.

Define material properties
Define linear thermal expansion and thermal conductivity of the polymer material, as well as hydromechanical parameters of water, such as viscosity, density, and velocity.

Establishing a fluid-structure coupling model
A fluid-structure coupling model is established by associating the linear thermal expansion of polymer with the Navier-Stokes equations.

Perform simulation calculations
Perform simulation calculations and observe the shrinkage of the polymer and the flow of water around it.

By analyzing the simulation results, information such as the velocity and pressure of the water flow around the polymer shrinkage can be obtained.

Reference:

COMSOL Multiphysics Modeling Guide, Chapter 6: Fluid-Structure Interaction(FSI), https://www.comsol.com/documentation/6.3/pdf/mode ling-guide.pdf

Wang, X., Chen, L., & Yang, W.(2017). A coupled simulation study on the fluid-solid interaction behavior of polymer shrinkage. Journal of Applied Polymer Science, 134(18), 45038.

dengyijie12306 注册会员
2023-02-28 05:27

COMSOL provides a three-dimensional fluid-structure coupling case that simulates a micromachining process and can be used to study the effects of solid shrinkage on fluid scenarios. For details, see

.

This model assumes that there is a micromachining rod in a pipe, which will shrink when it is hot pressed, and this shrinkage will produce temperature field, flow field and stress field, thus affecting the flow characteristics of the fluid. The parameters calculated in the model are: layer thickness of micromachining rod, processing temperature, fluid flow and velocity, and thermal expansion coefficient of solid material. The results will tell us how the micromachining rod shrinkage affects the fluid flow characteristics and how the temperature field, flow field and stress field are coupled.

dpfir23 注册会员
2023-02-28 05:27
fluid-structure coupling, which describes how a solid can produce pressure by squeezing the internal liquid when it is shrinking. The case involves a three-dimensional model, modeled using COMSOL's structural mechanics and fluid dynamics modules.

The basic idea of the case is that a solid model(which can be any shape) is placed in a liquid, simulating that the contraction of the solid compresses the liquid, creating pressure. Here are some steps:

1 First, create a solid model using COMSOL's Structural Mechanics module. Place the model in an enclosed space that represents the area containing the liquid.

2 Define material properties of the solid model, such as elastic modulus, Poisson's ratio, and linear expansion coefficient. These parameters will determine the behavior of the solid.

3 Define properties of the liquid, such as density, viscosity, and surface tension. These parameters will affect the behavior of the liquid.

4 Create a fluid dynamics module in COMSOL and define the enclosed space of the model as the liquid region. The Navier-Stokes equations are used to describe the motion of the fluid and appropriate boundary conditions are applied.

5 Define the initial values and boundary conditions of the fluid model. In this case, you need to specify initial values for the liquid and wall conditions for the solid surface.

6 Finally, the solid and fluid models are coupled together using COMSOL's fluid-structure coupling capability. This will ensure that the contraction of the solid can create pressure, while also taking into account the force of the liquid on the solid.

Note: The exact modeling details will vary from model to model. The above steps provide only a basic idea. For more detailed modeling details, refer to COMSOL's official documentation or contact COMSOL technical support. Next, we can consider some details and parameter Settings in the model:

Solid model: We can use a solid model of any shape, but we must make sure that it can be shrunk. You can use linear elastic or nonlinear material models from the structural mechanics module to describe the behavior of solids. In COMSOL, you can choose from a variety of material models, including linear elasticity, isotropic or anisotropic superelasticity, plasticity, and more. In this case, we can use the linear elastic material model.

Liquid model: We need to define the properties of the liquid, such as density, viscosity, surface tension, etc. In COMSOL, we can choose from a variety of fluid models, including ideal fluid, incompressible fluid, compressible fluid, and so on. In this case, we can use the incompressible fluid model because we assume that the density of the liquid remains constant.

Initial values and boundary conditions: We need to specify initial values and boundary conditions for the solid. In this case, we can define the solid surface as the wall condition of the solid, that is, not allowing the liquid to penetrate the solid surface. We also need to specify the initial value and flow boundary conditions for the liquid. These conditions can be determined on a case-by-case basis, for example if we want to simulate the flow of a liquid, we can set inlet and outlet boundary conditions around the solid.

fluid-structure coupling: In COMSOL, fluid-structure coupling can be achieved in two ways, one using a weakly coupled method and the other using a strongly coupled method. In this case, we can use the weakly coupled approach. In the weak coupling method, the fluid and solid models are solved separately, and then coupled by exchanging boundary data. This method is relatively simple, but can sometimes lead to a loss of accuracy.

The above is a basic example of fluid-structure coupling, which you can adjust and modify to suit your specific situation. In addition, you are advised to refer to official documents and relevant examples before using COMSOL for modeling.

dsy_8110 注册会员
2023-02-28 05:27

The following is a COMSOL fluid-structure coupling case involving the effect of solid deformation on a fluid.

Case description: A closed pipe contains a certain amount of fluid, and inside the pipe is a deformable elastic body. When the elastomer deforms, it affects the fluid inside the pipe, resulting in changes in the pressure and velocity of the fluid.

In COMSOL, you first need to build a 3D model, including the pipe and elastomer. You can model it using CAD tools and then import it into COMSOL.

Define the physical field in the model. In this case, you need to define the solid mechanics module and the fluid mechanics module. In the solid mechanics module, the material properties and boundary conditions of elastomers are defined. In the fluid mechanics module, the initial conditions, boundary conditions, and required physical parameters of the fluid are defined.

Coupling. In COMSOL, you can use a physical coupling interface to couple two physical fields together. In this case, the solid mechanics module and the fluid mechanics module need to be coupled.

Set the solver. In COMSOL, different solvers can be selected to solve the model. In this case, a steady-state or transient solver can be chosen, depending on the specific requirements of the model.

Run the simulation and analyze the results. After the simulation runs, you can analyze the results of the model. Information such as elastomer deformation, fluid velocity and pressure distribution can be viewed.

The above is an example that can be modified for specific model requirements.

In the case of 3D model solid shrinkage of internal liquid, consider the following scenario: a cylindrical solid material contains a certain amount of liquid. When heated, the material shrinks and deforms, resulting in an increase in the pressure of the internal liquid, and finally a hole in the solid material is squeezed out. In COMSOL, you can use the thermodynamics module and the solid mechanics module to model and simulate.

It should be noted that specific modeling methods and simulation processes depend on specific problems and need to be analyzed and designed according to the actual situation.
A classic example of the effect of solid deformation on a fluid is the compression of a gel to simulate the effect of cell pressure. In this case, the deformation of the gel(solid) has an effect on the fluid(liquid) around it because the gel squeezes the fluid around it.

In COMSOL, you can use the Fluid-Structure Interaction(FSI) module to simulate this situation. Here is a simple step to set up this case:

Create a three-dimensional model containing a field containing gels and fluids. The Geometry module in COMSOL can be used for modeling.

Import material properties. Material properties of gels and fluids, such as density, viscosity, and elastic modulus, need to be defined.

Define the physical field. The mechanical and mechanical behaviour of gels, such as stress-strain relationships, and the flow equations of fluids, such as the Navier-Stokes equations, need to be defined.

Set boundary conditions. Boundary conditions need to be set for gels and fluids, such as fixed or free flow of boundaries.

Simulate and analyze the results. The model can be solved and the effects of gel deformation on fluid flow, such as changes in fluid velocity and pressure distribution, can be observed.

Note that this case requires some knowledge of material properties and physical properties of gels and fluids, as well as familiarity with COMSOL's modeling and solution process

crd0605 注册会员
2023-02-28 05:27

Case Description : Consider a sealed elastic solid water bag with a small vertical hole above it. At the beginning, the inside of the water bag is filled with water, and the water level is higher than the hole. We want to study the effect of solids on the flow of liquid inside them as they contract. COMSOL enables modeling of multiple physical fields, including structural mechanics and fluid mechanics.

Model building :
(1) Create a three-dimensional model containing elastic solid water bags and water. Modeling is done using the geometric modeling module in COMSOL.
(2) Add the solid state physical field to the model. In the solid state physics field setup, select the elastic module and define its material properties.
(3) In the fluid physical field setting, treat water as a fluid and add the Navier-Stokes equations to describe the motion of the fluid. The function of Free surface coupling in fluid physical fields is used to coupling fluid physical fields with solid physical fields.
(4) Set the wall condition to be fixed to simulate the tightness of the water bag.
(5) In the boundary setting of solid physical field, the hole is set as the displacement boundary condition. By setting the displacement of the hole, the process of solid shrinkage can be simulated.
(6) In the boundary setting of the fluid physical field, set the hole as the pressure outlet condition. At the beginning, the pressure inside the bag is higher than the atmospheric pressure at the orifice, so the water will flow out of the orifice. As the solid contracts, the position of the orifice changes, changing the velocity and pressure of the water flow.
(7) The model is solved and the results of water flow and solid deformation are plotted.

duoqingduoyi 注册会员
2023-02-28 05:27

The following answer is based on ChatGPT and GISer Liu:
The following is a possible example of COMSOL fluid-structure coupling, which shows how solid shrinkage can squeeze out internal liquid:

1. Create a 3D model: First, create a 3D model in COMSOL containing a solid region and a liquid-filled region. Set appropriate boundary conditions and material properties in the model.

2. Define physical fields: Define physical fields in COMSOL. For the solid region, the structural mechanics module can be selected to describe the deformation and stress states of the solid. For the liquid region, you can select the hydrodynamics module, which describes the flow and pressure distribution of the fluid.

3. Establish coupling: Establish coupling in COMSOL. Coupling can be achieved by adding coupled physical fields. For example, a fluid mechanics module and a structural mechanics module can be coupled by adding a fluid pressure field to the structural mechanics module. Coupling will cause the liquid to be forced out when the solid shrinks.

4. Set boundary conditions: Set the appropriate boundary conditions in COMSOL. For example, you can set fixed boundary conditions for solid surfaces and free surface or wall boundary conditions for liquid surfaces.

5. Set up solver: Select the appropriate solver in COMSOL. Typically, Coupling solvers, such as the Sequential Coupling algorithm, are used.

6. Run the simulation: Run the simulation in COMSOL and observe the results. The effects of solid contraction on liquid flow, such as pressure and velocity distribution, can be analyzed. The effect of liquid flow on solid stress can also be analyzed, such as the deformation and stress distribution of solids.

In this case, structural mechanics module and fluid mechanics module are mainly used to realize the influence of solid shrinkage on liquid through coupling. It should be noted that this case is only a simple example, the specific model and parameters need to be adjusted and optimized according to the actual situation.

duliuji10 注册会员
2023-02-28 05:27

Example 1: This case mainly simulates the dynamic fluid-solid coupling phenomenon of a die casting mold in the process of liquid casting, in order to solve the interaction between the liquid flow state and the air flow state in the process of solid structure deformation of materials in the die casting mold. It is proposed to consider the influence of air pressure deformation and temperature(air and liquid) on the liquid flow state and solid structure deformation. And the effect of temperature on the viscosity of the liquid in the fluid.
This case is used to simulate the dynamic fluid-structure coupling phenomenon of the plastic printing micropump. Considering the deformation of the solid structure and the interaction between the flow bodies in the micropump, the influence of pressure on the deformation of the solid structure and the influence of temperature on the surface tension, heat transfer and rheology of the fluid is proposed.
The Flow-Structure Interaction module in COMSOL Multiphysics can be used to simulate the effects of solid deformation on fluids.
ComSol has a large case library in 3D models. Can help you provide strong support for such research and design topics. One example can help you understand the fluid effects caused by the deformation of solids. Called the Thermal Deformation Clamp, it mimics a composite end cap in which the deformation of a solid material may cause a fluid to flow. This case study will help you understand the fluid effects caused by solid deformation, such as pressure gradient, fusion ratio, and fluid flow rate, and the resulting effect on the performance of the clamping device.
Typical Comsol fluid-structure coupling case 1 -- Formation of low-density bubbles due to shrinkage of solidified liquid: In the laboratory, in order to simulate the heat exchange environment between low-density bubbles and solids, basic physical mechanisms such as fluid flow(gas in bubbles) and structural mechanics(contraction to form bubbles) are required, so fluid-structure coupling technology is needed for simulation.
Typical Comsol fluid-structure coupling case 2 -- Fast deforming porous materials: In this typical case, we will combine the fast deforming materials(such as porous media under fluid loading) in the structural mechanics model with the fluid flow model, and use the fluid-structure coupling technology to simulate the material deformation and fluid flow conditions after loading.

dqxcz1 注册会员

Publish Time
2023-02-28 05:27
Update Time
2023-02-28 05:27