### 6.3.5. Reduction of Application Uncertainties

Application uncertainties cannot always be avoided because the missing information can frequently not be recovered. The uncertainty can be minimized by interaction with the supplier of the test case. The potential uncertainties have to be documented before the start of the CFD application.

In the case that the assumptions have to be made concerning any input to a CFD analysis, they have to be communicated to the partners in the project. Alternative assumptions have to be proposed and the sensitivity of the solution to these assumptions has to be evaluated by case studies (alteration of inflow profiles, different locations for arbitrary boundary conditions, and so on).

Recommendations are:

- Identify all uncertainties in the numerical setup:

  - Geometry reduction

  - Boundary condition assumptions

  - Arbitrary modeling assumptions, for example, bubble diameter, and so on.

- Perform a sensitivity analysis with at least two settings for each arbitrary parameter.

- Document the sensitivity of the solution on the assumptions.

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