yes, its a latest version.

You need to clarify the boundary conditions for the model.

Niharika Dutt Thank you for the response.

In my application, a micro sized unit, that has a gold layer inside its body is submerged in a microfluidic well. The fluid domain is represented by the cuboid object in above attached file. The gold layer inside the microunit needs to be heated using a laser beam. Outside boundaries of the cuboid are open to outside environment and heat dissipation would happen through these boundaries too. It is required to study about convective flow generation in this situation.

Modeling laser-induced convective flows in COMSOL involves simulating the interaction of laser heating with a fluid medium, resulting in temperature gradients that drive convective flows. This type of simulation typically couples thermal, fluid, and, in some cases, electromagnetic physics. Below are the steps to create such a model:

1. Set up the Geometry:

• Define the geometry of the domain, which could include a fluid-filled container and the region where the laser beam interacts.
• Consider a smaller domain to reduce computational costs while focusing on the region of interest where the laser is applied.

2. Select the Physics Interfaces:

• Use the Heat Transfer in Fluids interface to model heat conduction and convection in the fluid.
• Use the Laminar Flow interface to solve for fluid flow due to convection. If the fluid flow is turbulent, select the Turbulent Flow interface instead.
• For laser heating, if you want to simulate how the laser interacts with the material, consider adding the Electromagnetic Waves (for high-frequency lasers) or Heat Source (for simpler applications) interface.

3. Define Material Properties:

• Assign material properties to the domain, such as thermal conductivity, density, specific heat capacity, and viscosity.
• For the fluid region, use the built-in material library or create a custom material. For water or air, use pre-defined properties, ensuring they are temperature-dependent if necessary.

4. Set up Laser Heating:

• If using the Heat Transfer in Fluids interface, define a Heat Source corresponding to the laser's energy deposition.
• Specify the power, location, and shape of the laser beam. This can be a Gaussian profile or another custom function.
• For more detailed simulations, use the Electromagnetic Waves interface to model the propagation and absorption of the laser energy. Define the wavelength, beam profile, and absorption characteristics of the material.

5. Set up the Fluid Flow:

• Set up the Laminar Flow or Turbulent Flow interface depending on the flow characteristics.
• Define initial and boundary conditions for the fluid. For example, set No Slip boundary conditions for walls.
• Include Gravity if natural convection is a driving force in your model.

6. Couple Heat Transfer and Fluid Flow:

• Use Multiphysics coupling nodes to link the Heat Transfer in Fluids and Laminar Flow interfaces.
• Enable Non-Isothermal Flow coupling to account for the temperature gradients driving convection.
• Specify whether the flow is driven by Buoyancy Force or Thermal Expansion.

7. Define Boundary and Initial Conditions:

• For heat transfer, specify boundary conditions such as Convective Heat Flux, Inward Heat Flux, or Surface-to-Ambient Radiation if the laser is interacting with an external surface.
• For fluid flow, define velocity or pressure boundary conditions at inlets/outlets.

8. Mesh the Geometry:

• Create a finer mesh in regions where the laser interacts with the fluid and coarser meshes in other regions to optimize computational costs.
• Use Boundary Layer Meshing near walls and surfaces to accurately capture convective flow behavior.

9. Set Up the Study:

• Choose a Time-Dependent study if simulating transient behavior (e.g., laser being turned on and off).
• Choose a Stationary study if looking for steady-state solutions.
• Set appropriate time steps and tolerances for numerical stability and accuracy.

10. Run the Simulation:

• Run the simulation and monitor key variables like temperature, velocity, and pressure fields to ensure convergence.
• If the solution does not converge, consider refining the mesh or adjusting solver settings.

11. Post-Processing and Visualization:

• Visualize temperature contours and flow fields using streamlines or arrow plots.
• Evaluate quantities like maximum temperature, velocity profiles, and heat flux to analyze the effect of laser heating on the fluid.

Additional Considerations:

• If simulating phase change due to laser heating (e.g., evaporation), add the Phase Change or Two-Phase Flow interfaces to model the transition.
• For high laser power or very small scales, consider including the Marangoni Effect (surface tension-driven flow) if surface tension variations are significant.

By following these steps and adjusting for specific laser parameters and fluid properties, you can effectively model laser-induced convective flows in COMSOL.