How to make variants of a model

1. Alternatives

Use copy & paste
Parameterizing
Model variations
- Structural changes of the model

2. Copy & paste

Method
- Copy → paste → modify model
- Repeat for all variants of the model

3. Parameterizing

Method
- Parameterize the model
- Change model by changing the values of the parameters in the condition

4. Model variations

Method
- Structural change of the model
- Can be combined with parameterizing of the model
- Change model by selecting model variation and values of the parameters in the condition

4.1. Summary

Table 1. How to make variants of a model - pros & cons

Method

Pros

Cons

Copy & paste

Easy

Many, almost identical, models

If you want to change something in the model, you have to change all of them and maintenance becomes an issue.

Parameterizing

Easy and flexible to use.

Less maintenance

Allows for complex modelling.

Suitable for running in workflows & workflow sets.

Requires more experience.

Can be more time consuming to set up the model.

Model variations

Can change and replace parts of the model.

Large models can be built quickly

Less maintenance

Advanced use of SIMA

5. Example: Riflex catenary riser

Task: Make three variants of the model

Uniform current profile
Sheared current profile
No current

5.1. Example using copy & paste

The environment for the uniform and sheared current profile are shown in Figure 1 and Figure 2. These two model have the same static loading, see Figure 3.

The environment for the case with no current profile are shown in Figure 4. The current is not included the static loads, Figure 4 b.

Using copy & paste method, you will end up with three almost identical models, Figure 5.

By defining two environments, one could reduce the number of models to two as the environment is input to the condition Figure 5.

Figure 1. Model with uniform current profile

Figure 2. Model with sheared current profile

Figure 3. Model with uniform & sheared current profile - Static loading

Figure 4. Model with waves only (no current)

a) Environment	b) Static loading

Figure 5. Copy & paste - three models

5.2. Example: parameterizing of the model

Using parameterizing and changing the values of the parameters, you can model the two current profiles using the same environment, Figure 6. To run the model with uniform and sheared current profiles, you create two conditions and change the values of the parameters defining the current velocities, cur_lev1 and cur_lev2, Figure 7.

However, to run the model with no current, you still have to create a new model since changing the the static loading is a structural change of the model. This can not be handled by parameters on its own.

Using parameters, you will have one model with one current profile and another model which covers the case with no current, Figure 8.

Figure 6. Model with uniform and sheared current profile

Figure 7. Model with uniform & sheared current profile - Two conditions

Figure 8. Parameterizing - two models

5.3. Example: Model variation

The set-up for a model with uniform and sheared current profile are shown in Figure 9 and Figure 10. The two conditions are referring to the same environment, but the value of the variable cur_lev2 is different in the two cases.

The run the model with no current, teh condition is referring to an environment with no current. In addition, a structural change is required to get the static loading correct, Figure 11.

Using model variation and combining this with parameterizing, you can reduce the number of models to one, Figure 12.

The examples in Figure 12 are included in the Examples/Riflex/ section.