Specify an Analysis Type and Physical Features

If you want to specify a coordinate-dependent or time-dependent value, click Dependency after clicking the corresponding Value cell (see “Dependency” for details).

• Select the Fluid Flow check box if you want to analyze fluid flows.

• Select the Conduction check box if you want to analyze heat transfer in solid bodies in contact with the fluid (conjugate heat transfer problem).

  See “Conduction” for details.

• Select the Radiation check box if you want to enable surface-to-surface radiation in conjugate heat transfer analysis.

  The Conduction option will be enabled automatically.

  See “Radiation” for details.

• Select the Time-dependent check box if your problem is transient (i.e., unsteady).

  In the Wizard dialog additionally specify the analysis physical time in the Total analysis time box, the time step of results outputs in the Output time step box.

  You can modify these settings in the Calculation Control Options dialog box (see “Calculation Control Options” for details).

  See “Time-Dependent Analysis” for details.

• Select the Gravity check box if you need to take gravitational effects into account, and specify the acceleration due to gravity X, Y, and Z components in the Global Coordinate System (see “Global Coordinate System” for details).

  For time-dependent analyses, you can specify the gravitational acceleration vector dependent on time by clicking Dependency .

  Note:

  If liquids are used, check to see that the densities specified in Engineering Database are dependent on the fluid temperature.

  Restriction:

  If gases are used, you cannot use Gravity when the High Mach number flow option is enabled.

  See “Gravitational Effects” for details.

• Select the Rotation check box if you want to specify either Local region(s) of rotation or the Global rotating reference frame.

  For a Global rotating reference frame you need to specify the Reference axis and the Angular velocity.

  Restriction:

  You cannot use Rotation when the High Mach number flow option is enabled.

  See “Rotation” for details.

• Select the Free Surface check box if you want to model two immiscible fluids with an interface between them.

  The Time-dependent option will be enabled automatically.

  Restriction:

  You cannot use Free Surface when any options including phase transitions (for example Humidity, Condensation, Cavitation) are enabled.

  See “Free Surface” for details.

• Analysis type. Select either Internal or External type of the flow analysis:

  • Internal flow analysis concerns flows bounded by outer solid surfaces, e.g., flows inside pipelines, fittings, tanks, buildings, etc. To perform an Internal flow analysis, the model must be fully closed. To make sure the model is closed use Check Geometry (see “Check Geometry” for details).

  • External flow analysis concerns flows not bounded by outer solid surfaces, but only by the Computational Domain boundaries (see “Computational Domain” for details). In this case the solid model is fully surrounded by the flow, e.g., flows over aircraft, automobiles, buildings, etc. If you want to analyze both internal and external flows simultaneously, e.g. flows over and through a building, the analysis is treated as an External analysis in Flow Simulation.

• Geometry recognition. Select the way how Flow Simulation operates with the model components to get solid and fluid bodies. This option affects the fluid volume recognition, invalid geometry and the preparation time (see “Recognize a Fluid Volume”).

  • CAD Boolean. Flow Simulation operates with the model components to get solid and fluid bodies by using SOLIDWORKS boolean operations.

  • Preprocessor Boolean. Flow Simulation operates with the model components to get solid and fluid bodies by using its own algorithm for boolean operations instead of the SOLIDWORKS boolean operations (see “Check Geometry”).

  • Mesh Boolean. The computational mesh creates for each component separately. Then Flow Simulation operates with the model components to get solid and fluid bodies by using the computational mesh for boolean operations instead of the SOLIDWORKS boolean operations. This option also supports facet and mesh geometry (also known as “convergent geometry”).

    CAD boolean diagnostics. When checked, Flow Simulation operates with the model components to check all project conditions by using SOLIDWORKS boolean operations.

• Also you can select the additional options to reduce computational resource requirements for the complex models with internal spaces that are not involved in the flow analysis.

  Before beginning the calculation, analyzes the model and identifies all inner cavities. Each of these cavities is considered as a flow region and a computational mesh is constructed inside the cavities. You can use one of two options for reducing the required system resources:

  • Exclude cavities without conditions. In both Internal and External flow and heat transfer analyses select this option if you want to exclude closed internal spaces with no Boundary Conditions or Fans specified on their surfaces.

  • Exclude internal spaces. Allows you to disregard closed internal spaces in External flow analyses.

  Both procedures do not affect the model but allow you to avoid unnecessary mesh refinements and flow calculations in non-analyzed model regions. If you select these options the corresponding spaces and cavities are filled with solid.

  Note:

  Excluding internal spaces or cavities may cause wrong results if you analyze heat exchange between solid parts and fluid volumes.

• In the Wizard dialog, click Next or click a link on the Navigator pane to switch to the corresponding tab of the Wizard.

• In the General Settings dialog, click Apply to update and proceed with settings.

  - or -

  Click OK to apply the changes and exit the dialog.