 Here is a basic example of how you might structure your Python script using the PyAEDT library to perform a multiphysics analysis. Please note that this is a simplified example and you may need to adjust it according to your specific project requirements.

```python
from aedt import *
from aedt.hfss import *
from aedt.mechanical import *

# Set graphical mode
aedt.set_graphical_mode(True)

# Download and open a project
aedt.open_project('path_to_your_project.prj')

# Start HFSS with a specified version
hfss = HFSS(version='2021')
hfss.start()

# Start Circuit and add the HFSS dynamic link component to it
circuit = aedt.active_design.circuits.add('My Circuit')
dynamic_link = circuit.components.add(hfss)

# Set up dynamic link options
dynamic_link.options.solver_type = 'AC'
dynamic_link.options.frequency_range_start = 1e9
dynamic_link.options.frequency_range_end = 1e11

# Create ports and excitations
port1 = dynamic_link.ports.add('Port1', 'Port1', 'Port1')
excitation = dynamic_link.excitations.add('Sine', 'Port1', 1, 1e9)

# Create a setup and solve the circuit, pushing excitations to the HFSS model
setup = circuit.setups.add('Setup1')
setup.solve()

# Start Mechanical and copy bodies from the HFSS project
mechanical = aedt.active_design.mechanicals.add('My Mechanical')
mechanical.start()
mechanical.bodies.copy_from_hfss(dynamic_link)

# Get losses from HFSS and assign the convection to Mechanical
losses = dynamic_link.get_losses()
mechanical.materials.add('Losses', losses)
mechanical.convection.add('Convection', 'Losses', 10)

# Plot the model
mechanical.plot()

# Solve and plot the thermal results
mechanical.solve()
mechanical.plot_results('Temperature')

# Release AEDT
aedt.quit()
```

This script assumes that you have a project already set up in AEDT and that you have the necessary permissions to run the script. Also, please replace `'path_to_your_project.prj'` with the actual path to your project file.

Remember to install the PyAEDT library before running the script:

```bash
pip install pyAEDT
```