ANSYS CFD FLOTRAN Analysis Guide
Table of Contents
ANSYS CFD FLOTRAN Analysis Guide Table of Contents (UP19980818 )
Title, Disclaimer of Warranty and Liability
Preface
Topics in This Manual
Topics in Other ANSYS Manuals
Conventions This Manual Uses
The ANSYS Product Family
1 Overview of FLOTRAN CFD Analyses
1.1 What Is FLOTRAN CFD Analysis?
1.2 Types of FLOTRAN Analyses
1.2.1 Laminar Flow Analysis
1.2.2 Turbulent Flow Analysis
1.2.3 Thermal Analysis
1.2.4 Compressible Flow Analysis
1.2.5 Non-Newtonian Fluid Flow Analysis
1.2.6 Multiple Species Transport Analysis
2 The Basics of FLOTRAN Analysis
2.1 Characteristics of the FLOTRAN Elements
2.1.1 Element FLUID141
2.1.2 Element FLUID142
2.1.3 Other Element Features
2.2 Using the FLOTRAN Elements: Considerations and Restrictions
2.2.1 Limitations on FLOTRAN Element Use
2.3 Overview of a FLOTRAN Analysis
2.3.1 Determining the Problem Domain
2.3.2 Determining the Flow Regime
2.3.3 Creating the Finite Element Mesh
2.3.4 Applying Boundary Conditions
2.3.5 Setting FLOTRAN Analysis Parameters
2.3.6 Solving the Problem
2.3.7 Examining the Results
2.4 Files the FLOTRAN Elements Create
2.4.1 The Results File
2.4.2 The Print File (Jobname.PFL)
2.4.3 The Nodal Residuals File
2.4.4 The Restart File
2.4.5 Restarting a FLOTRAN Analysis
2.5 Convergence and Stability Tools
2.5.1 Relaxation Factors
2.5.2 Inertial Relaxation
2.5.3 Artificial Viscosity
2.5.4 Velocity Capping
2.5.5 The Quadrature Order
2.6 What to Watch For During a FLOTRAN Analysis
2.6.1 Deciding How Many Global Iterations to Use
2.6.2 Convergence Monitors
2.6.3 Stopping a FLOTRAN Analysis
2.7 Evaluating a FLOTRAN Analysis
2.8 Verifying Results
3 An Example of FLOTRAN Analysis
3.1 Example of a Laminar and Turbulent FLOTRAN Analysis
3.1.1 The Example Described
3.2 Approach and Assumptions
3.2.1 Dimensions and Properties
4 FLOTRAN Laminar and Turbulent Incompressible Flow
4.1 Characteristics of Fluid Flow Analysis
4.2 Activating the Turbulence Model
4.2.1 The Role of the Reynolds Number
4.2.2 Determining Whether an Analysis Is Turbulent
4.2.3 Turbulence Ratio and Inlet Parameters
4.2.4 Turbulence Models
4.2.4.1 Standard k- Model (default)
4.2.4.2 Zero Equation Turbulence Model (ZeroEq)
4.2.4.3 Re-Normalized Group Turbulence Model (RNG)
4.2.4.4 New k- Model due to Shih (NKE)
4.2.4.5 Non-linear Model of Girimaji (GIR)
4.2.4.6 Shih, Zhu, Lumley Model (SZL)
4.3 Meshing Requirements
4.4 Flow Boundary Conditions
4.5 Strategies for Difficult Problems
5 FLOTRAN Thermal Analyses
5.1 Thermal Analysis Overview
5.2 Meshing Requirements
5.3 Property Specifications and Control
5.4 Thermal Loads and Boundary Conditions
5.4.1 Applying Loads
5.4.1.1 Applying Loads Using Commands
5.4.1.2 Applying Loads Using the GUI
5.4.1.3 Solutions
5.5 Solution Strategies
5.5.1 Constant Fluid Properties
5.5.2 Forced Convection, Temperature Dependent Properties
5.5.3 Free Convection, Temperature Dependent Properties
5.5.4 Conjugate Heat Transfer
5.6 Heat Balance
5.7 Examples of a Laminar, Thermal, Steady-State FLOTRAN Analysis
5.7.1 The Example Described
5.8 Doing the Sample Analysis (Command Method)
5.9 Doing the Sample Analysis (GUI Method)
5.9.1 Finishing Your Analysis
5.10 Where to Find Other FLOTRAN Analysis Examples
6 FLOTRAN Transient Analyses
6.1 Time Step Specification and Convergence
6.2 Terminating and Getting Output from a Transient Analysis
6.3 Applying Transient Boundary Conditions
7 FLOTRAN Compressible Analyses
7.1 Requirements for Compressible Analysis
7.2 Property Calculations
7.3 Boundary Conditions
7.4 Structured vs. Unstructured Mesh
7.5 Solution Strategies
7.5.1 Inertial Relaxation
8 Specifying Fluid Properties for FLOTRAN
8.1 Guidelines for Specifying Properties
8.2 Fluid Property Types
8.2.1 Property Types for Specific Heat
8.2.2 Property Types for Density and Thermal Conductivity
8.2.3 Property Types for Viscosity
8.2.4 General Guidelines for Setting Property Types
8.2.5 Density
8.2.6 Viscosity
8.2.7 Specific Heat
8.2.8 Thermal Conductivity
8.3 Initializing and Varying Properties
8.3.1 Activating Variable Properties
8.4 Modifying the Fluid Property Database
8.5 Using Reference Properties
8.6 Using the ANSYS Non-Newtonian Flow Capabilities
8.6.1 Activating the Power Law Model
8.6.2 Activating the Carreau Model
8.6.3 Activating the Bingham Model
8.7 Using User-Programmable Subroutines
9 FLOTRAN Special Features
9.1 Coordinate Systems
9.2 Rotating Frames of Reference
9.3 Swirl
9.4 Distributed Resistance/Source
10 FLOTRAN CFD Solvers and the Matrix Equation
10.1 Which Solver Should You Use?
10.2 Tri-Diagonal Matrix Algorithm
10.3 Semi-Direct Solvers
10.3.1 Preconditioned Generalized Minimum Residual (PGMR)
Solver
11 Multiple Species Transport
11.1 Overview of Multiple Species Transport
11.2 Mixture Types
11.2.1 Dilute Mixture Analysis
11.2.2 Composite Mixture Analysis
11.2.3 Composite Gas Analysis
11.3 Doing a Multiple Species Analysis
11.3.1 Establish the Species
11.3.2 Choose an Algebraic Species
11.3.3 Adjust Output Format
11.3.4 Set Properties
11.3.5 Specify Boundary Conditions
11.3.6 Set Relaxation and Solution Parameters
11.4 Doing a Heat Exchanger Analysis Using Two Species
11.5 Example Analysis Mixing Three Gases
12 Advection Discretization Options
12.1 Introduction
12.2 Using SUPG
12.3 Strategies for Difficult Solutions