《CFX4培训》（英文版）Lecture 4 Geometry Creation in CFX-Build

Lecture 4 CFX-Build Geometry Creation in CFX-Build CFX-4.3V4.3.1H CFX-4 Introductory Training(Dec 1999

CFX-4 Introductory Training (Dec 1999) 4 -1 CFX-4.3 V4.3.1H Lecture 4 Geometry Creation in CFX-Build CFX-Build

Tolerance公差 The initial tolerance is important for geometry construction and grid construction The preferred method to set the tolerance is to work from the Preferences pull down menu and select Global CAX-Build 4.3 File Group viewport viewing Display preferences Tools 恿■&cFx Geometry Constraints Patches Periodi Analysis. 囵團圓囻■ω回回囤阃国厕圖團國函圖蹰翌翌 mil_prefanalysisset analysis.-prof("CFx 4","Flu Key map. Geometry. MaIn Form 4-2 CFX-4.3V4.3.1H CFX-4 Introductory Training(Dec 1999

CFX-4 Introductory Training (Dec 1999) 4 -2 CFX-4.3 V4.3.1H Tolerance 公差 The initial tolerance is important for geometry construction and grid construction. The preferred method to set the tolerance is to work from the Preferences pull down menu and select Global

Tolerance Set the global model tolerance to one -tenth of the expected minimum cell size Global Preferences 9 Message options E Auto Update const Plane Default coordinate Frame oord 0 Default construction plane Global Model Tolerance Apply CFX-4.3V4.3.1H CFX-4 Introductory Training(Dec 1999

CFX-4 Introductory Training (Dec 1999) 4 -3 CFX-4.3 V4.3.1H Tolerance Set the Global Model Tolerance to one-tenth of the expected minimum cell size

Tolerance Example 1 unit length Desire 10 uniform cells across length Tolerance should be set to 0.01 CFX-4.3V4.3.1H CFX-4 Introductory Training(Dec 1999

CFX-4 Introductory Training (Dec 1999) 4 -4 CFX-4.3 V4.3.1H Tolerance Example Desire 10 uniform cells across length. 1 unit length Tolerance should be set to 0.01

Units It is possible to work in any unit system for geometry creation(ft, in, mm, cm, m) We suggest scaling the geometry to metric units on the analysis form for geo file creation Geom.Scale Factors口 0254 0254 Defaults CFX-4.3V4.3.1H CFX-4 Introductory Training(Dec 1999

CFX-4 Introductory Training (Dec 1999) 4 -5 CFX-4.3 V4.3.1H Units It is possible to work in any unit system for geometry creation (ft, in, mm, cm, m). We suggest scaling the geometry to metric units on the Analysis form for geo file creation

Units However, appropriate units should be used to build the geometry. (Hint: try to keep the dimensions, di, of the geometry in the range 0. 01<d <100. This will reduce the possibility of floating point errors Any consistent system of units can be used CFX-4.3V4.3.1H CFX-4 Introductory Training(Dec 1999

CFX-4 Introductory Training (Dec 1999) 4 -6 CFX-4.3 V4.3.1H Units However, appropriate units should be used to build the geometry. (Hint: try to keep the dimensions, di , of the geometry in the range 0.01<di<100.) This will reduce the possibility of floating point errors. Any consistent system of units can be used

ABA TECHnoloG Steps in Geometry Creation Geometry build wire frame using points, curves, surfaces and solids Constraints define constraints for solids with area mismatch Patches define boundary conditions(inlet, outlet, walls) Mesh mesh all surfaces Analysis generate internal volume mesh and geo file CFX-4.3V4.3.1H CFX-4 Introductory Training(Dec 1999

CFX-4 Introductory Training (Dec 1999) 4 -7 CFX-4.3 V4.3.1H Steps in Geometry Creation - build wire frame using points, curves, surfaces, and solids. - define constraints for solids with area mismatch. - define boundary conditions (inlet, outlet, walls). - mesh all surfaces. -generate internal volume mesh and geo file. Geometry Constraints Patches Mesh Analysis

Geometry Building points(cyan青蓝色 curves (yellow) vector function of a parametric variable points created implicitly when constructing curves surfaces, and solids not necessary to construct explicit points and then higher order entities note differences between explicit curves and implicit edges CFX-4.3V4.3.1H CFX-4 Introductory Training(Dec 1999

CFX-4 Introductory Training (Dec 1999) 4 -8 CFX-4.3 V4.3.1H Geometry Building points (cyan青蓝色). curves (yellow) - vector function of a parametric variable - points created implicitly when constructing curves, surfaces, and solids - not necessary to construct explicit points and then higher order entities - note differences between explicit curves and implicit edges

Geometry Building simple surfaces(green) are composed of 4 edges and 4 vertices construct solids using simple surfaces only simple surfaces are meshed using the isomesher CFX-4.3V4.3.1H CFX-4 Introductory Training(Dec 1999

CFX-4 Introductory Training (Dec 1999) 4 -9 CFX-4.3 V4.3.1H Geometry Building simple surfaces (green) are composed of 4 edges and 4 vertices > construct solids using simple surfaces only > simple surfaces are meshed using the isomesher

Geometry Building solids(blue) characterized by a bounding set of surfaces 6 surfaces. 8 vertices parametric function of 3 variables(L,J, K) meshed with the isomesher non-parametric solids(B-rep) cannot be used to create a structured grid 4-10 CFX-4.3V4.3.1H CFX-4 Introductory Training(Dec 1999

CFX-4 Introductory Training (Dec 1999) 4 -10 CFX-4.3 V4.3.1H Geometry Building solids (blue) - characterized by a bounding set of surfaces - 6 surfaces, 8 vertices - parametric function of 3 variables (I,J,K) - meshed with the isomesher - non-parametric solids (B-rep) cannot be used to create a structured grid