## Chapter 24: Expert Control Parameters

This chapter describes:

- Modifying Expert Control Parameters

All geometry, domain, boundary condition, mesh, initial value and solver parameter information is written to the CFX-Solver Input (`.def`) File.

The CFX-Solver input file contains the relevant information required by the CFX-Solver to conduct the CFD simulation. This information mainly consists of numerical values that set up the simulation, as well as controls for the CFX-Solver.

Many of these parameters are set in CFX-Pre. For example, on the Solver Control panel, you can set the accuracy of the numerical discretization. Expert control parameters are settings that do not require modification for the majority of CFD simulations, and cannot immediately be set through the CFX-Pre interface. For details, see CFX-Solver Expert Control Parameters in the CFX-Solver Modeling Guide.

Note that expert control parameters are only intended for use by customers who are experienced in using CFX, or who have been instructed to use expert control parameters by ANSYS customer support. Use of these parameters is not fully supported, and may cause unexpected or unintended consequences for both the performance of the CFX-Solver and the quality of the results. For details, see When to Use Expert Control Parameters in the CFX-Solver Modeling Guide.

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