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SmartNumerics Simulation Solutions Inc.

Copyright SmartNumerics Simulation Solutions Incorporated, 2020, All Rights Reserved.

The EasyFlowfield code was created to supply flow simulation solutions to engineers and scientists with modest budgets. It includes unique capabilities of interest to aircraft designers or hobbyists. If you do not have a technical background, you may still be able to obtain useful values such as airfoil lift, drag, pitching moment, drag polar, and aerodynamic center, by adapting sample applications supplied with EasyFlowfield. EasyFlowfield is available in a full version or as EasyFlowfield Basic.

EasyFlowfield comes with a set of tutorials which will help you start solving real world problems. A set of validation documents provides additional information on the capabilities and accuracy of EasyFlowfield.

Simulations are set up by running the EasyFlowfield Graphical User Interface (GUI). The EasyFlowfield GUI dialogs are organized into groups under several menu headings so that you can quickly select the simulation type and then omit unnecessary details or include required details related to the equations of state, the molecular properties, and turbulence modeling. A simple inviscid time-accurate simulation can be performed by merely specifying initial states and selecting one of several internally generated grids. Much more complex simulations can be performed with little additional effort. A large range of solution output options has been provided. The dialogs are organized in an intuitive manner, but if more information is needed, help files associated with each menu heading supply this along with numerous examples. The help files contain an abundance of useful advice.

EasyFlowfield Basic simulates inviscid, laminar, or turbulent compressible flow about an airfoil using robust and efficient finite-volume algorithms (see Figures 1 and 2). In addition, a single-block Cartesian grid with or without concentration of grid lines can be used to simulate flow in one-dimension (inviscid) or in a two-dimensional rectangular region or in a three-dimensional cuboid region. Both time-accurate (transient) and steady-state simulations can be performed.

Students can use EasyFlowfield Basic to determine how accurate the assumption of incompressible flow is for various flow speeds. Even a simple laminar pipe-flow simulation reveals interesting details of pressure and flow velocity. Try simulating a heated pipe to see the effect on friction.

The full version of EasyFlowfield offers substantially more capability. Inviscid, laminar, or turbulent compressible flow (gas or liquid) problems are solved on stationary (non-rotating) Cartesian or boundary conforming meshes using robust and efficient finite-volume algorithms. Two dimensional structured single-block, multiblock, o-grid, and c-grid meshes as well as single-block 1D grids and single-block 3D Cartesian grids can be generated internally. Internally generated or imported o-grids and c-grids can be used to simulate 2D flow over airfoils. Two-dimensional grids can be converted into three-dimensional grids and some three-dimensional grids can be converted into two-dimensional grids. Imported 3D structured multiblock grids can used to simulate flow over wings or more complex objects. EasyFlowfield typically uses one to six grid-blocks when performing a simulation. However, grids with up to 300 grid-blocks can be imported. For example, Figures 3 and 4 below show contours of pressure coefficient (Cp) for inviscid flow about a generic business jet. The simulation was performed on a 234-block grid (42 megabytes) using a preconditioned LU-SGS scheme in combination with multigrid. The sample grid was obtained from the CGNS website.

Both codes can be used to obtain aerodynamic forces and plots of pressure and friction coefficients along airfoil surfaces. Drag polar plots and plots of airfoil forces versus angle of attack can be obtained. The full version of EasyFlowfield can output lift and drag forces and plots of pressure and friction coefficients for flow over a wing simulated using an imported 3D grid.

Using the full version of EasyFlowfield, you can import externally generated structured single-block and multiblock boundary-conforming 2D and 3D grids using the CGNS and PLOT3D file formats. You can export structured 2D and 3D single block and multiblock grids using the CGNS and PLOT3D file formats. Using PLOT3D export dialogs, you can convert grids from 3D to 2D or from 2D to 3D. You also can exchange the number of cells in the x, y, and z (i.e., i, j, k) directions. You can split a selected block into two blocks and export the resulting grid in PLOT3D format. EasyFlowfield currently uses the Advanced Data Format. The Hierarchical Data Format (currently HDF5) is also supported.

Help files for EasyFlowfield may be opened by clicking on the following links which correspond to the EasyFlowfield GUI menu headings . A detailed overview of EasyFlowfield is presented in the first (left most) help file.

Validation and verification documents can be viewed by clicking on

A number of tutorials may be accessed by clicking on

The following video features validation results for turbulent transonic flow about the RAE2822 airfoil. The demo includes simulation of turbulent flow over a backward facing step, inviscid flow though a nozzle, inviscid flow about the NACA0012 airfoil, and a shock wave reflecting off a wedge.

EasyFlowfield generates aerodynamic center estimates for airfoils and wings using Computational Fluid Dynamics or experimental data. The aerodynamic center is typically defined as the point about which the pitching moment does not change
with angle of attack. More practically, the aerodynamic center may be defined as the point at which the pitching moment is almost constant over a substantial range of angle of attack.  Knowledge of the aerodynamic center is important in analyzing the longitudinal stability of an aircraft. Standard inviscid flow analysis for thin symmetric airfoils at small angles of attack locate the aerodynamic center at the quarter chord point. More advanced analysis as demonstrated in the following video shows that this is only approximately correct.

If your have a question or are interested in using EasyFlowfield or EasyFlowfield Basic, please click on

Figure 4 displays the convergence and aerodynamic force history for inviscid flow over the generic business jet. The initial simulation was performed on a subgrid with one-eighth of the original number of cells using two coarser subgrids. The solution at 1500 cycles was then automatically transferred to the original grid and the simulation was continued for an additional 1000 cycles with three subgrids. The lift and drag coefficients were computed by normalizing the pressure forces with the dynamic pressure and the estimated total wing, horizontal stabilizer, and body surface area projected onto the x-z plane (1970.3 ft²). The simulation was performed on a PC with 8 gigabytes of memory.