To address the discrepancy between simulated and experimental temperature distributions in WAAM using the GOLDAK double heat source equation, consider the following:

The discrepancy between your experimental and simulation results, where the simulated temperature at 10 mm from the deposition is not matching your experimental data, could arise from several factors. Here are some common reasons and solutions:

1. Inaccurate Heat Source Parameters

Problem: If the parameters in the Goldak double ellipsoidal heat source model (e.g., power input, dimensions of the ellipsoids, efficiency, etc.) are not properly calibrated, the heat distribution might not match reality.

Solution: Ensure the heat source parameters are calibrated based on experimental data. Adjust the semi-axes of the ellipsoid, heat distribution ratio, and efficiency to better fit the experimental results.

2. Material Properties

Problem: Incorrect thermal properties (thermal conductivity, specific heat, density, emissivity) of the substrate or filler material in the simulation may cause deviations.

Solution: Double-check that you are using temperature-dependent material properties if applicable. These properties can significantly influence heat conduction and dissipation.

3. Boundary Conditions

Problem: If boundary conditions (e.g., heat loss due to convection, radiation, or contact) are not realistic, it can lead to discrepancies.

Solution: Include realistic heat loss mechanisms such as convection and radiation. Ensure the heat transfer coefficient and emissivity values align with experimental conditions.

4. Thermocouple Placement in Simulation

Problem: The placement of the virtual thermocouple in the simulation may not perfectly replicate the experimental setup. For example, the mesh size at the thermocouple location might not capture local variations accurately.

Solution: Ensure the mesh resolution near the thermocouple location is fine enough to capture temperature gradients accurately. Confirm the virtual thermocouple is placed exactly 10 mm from the deposition zone.

5. Time Step and Solver Settings

Problem: Using an inappropriate time step or solver settings can lead to inaccuracies in transient temperature predictions.

Solution: Use a smaller time step for transient thermal analysis and ensure the solver settings are appropriate for heat transfer problems.

6. Substrate and Boundary Interaction

Problem: The interaction between the heat source, substrate, and deposited material may not be accurately modeled (e.g., thermal contact resistance or fusion layer issues).

Solution: Validate the thermal contact conditions and ensure proper coupling between the substrate and deposition.

7. Experimental vs. Simulated Environment

Problem: Experimental conditions such as preheating, ambient temperature, or substrate constraints might not be replicated in the simulation.

Solution: Match the initial and boundary conditions in the simulation to the experimental setup, including ambient temperature and preheating effects.

8. Heat Source Positioning

Problem: The positioning of the Goldak heat source in the simulation might not align perfectly with the experimental deposition path.

Solution: Ensure the moving heat source accurately follows the experimental deposition trajectory, and its velocity matches the experimental process.

Next Steps:

1. Revisit your simulation setup and identify discrepancies with experimental conditions.

2. Adjust heat source parameters to better match the observed temperature distribution.

3. Perform sensitivity analysis to understand which parameters (e.g., material properties, heat source size) most influence the temperature distribution.

4. If possible, use experimental data (e.g., from the thermocouples) to iteratively refine the simulation parameters.

You can watch these videos and instead of creating the partitions, use one part and instead of the load values use the subroutines! I think you'll get your answer!

1- https://www.youtube.com/watch?v=OOkXX_ZDCZQ&list=PLvACBM1uN9EqfmWZjxMjD6o5Fd0KQs9TV&index=4&ab_channel=FEAMaster

2- https://www.youtube.com/watch?v=QhHDY7CxvF8&list=PLvACBM1uN9EqfmWZjxMjD6o5Fd0KQs9TV&index=3&ab_channel=FEAMaster