autos,on ! auto time-stepping deltim,1e-5,1e-6,delt,on ! time step control outres,basic,all ! save all load step information physics,write,thermal ! write thermal physics file finish *do,i,1,ftime/tinc ! solution *do loop time=time+tinc ! increment time physics,read,emag ! read emag physics file /solu *if,i,eq,1,then tunif,100 ! initial temperature *else ldread,temp,last,,,,,rth ! read thermal analysis temperatures *endif solve ! solve harmonic analysis finish physics,read,thermal ! read thermal physics file /assign,esav,therm,esav ! redirect files for use in thermal restart /assign,emat,therm,emat /solu *if,i,gt,1,then antype,trans,rest ! thermal restart *endif time,time ! time at end of thermal run esel,s,mat,,2 ! select billet region ldread,hgen,,,,2,,rmg ! apply coupled joule heating load from emag esel,all solve finish /assign,esav ! reassign files to default /assign,emat *enddo ! end of solution looping finish save ! save database /post26 ! time-history postprocessor /show nsol,2,1,temp,,tempcl ! store temperature at billet centerline nsol,3,2,temp,,tempsurf ! store temperature at billet outer diameter plvar,2,3 ! plot temperature rise over time prvar,2,3 ! print temperature rise over time finish 2.8.2.10. Results Figure 2.18: “Temperature Response of Solid Cylinder Billet” shows the temperature results obtained in this analysis. Chapter 2: Sequentially Coupled Physics Analysis ANSYS Coupled-Field Analysis Guide . ANSYS Release 10.0 . 002184 . © SAS IP, Inc. 2–34 Figure 2.18 Temperature Response of Solid Cylinder Billet Section 2.8: Example Induction-heating Analysis Using Physics Environments 2–35 ANSYS Coupled-Field Analysis Guide . ANSYS Release 10.0 . 002184 . © SAS IP, Inc. 2–36 Chapter 3: The ANSYS Multi-field (TM) Solver - MFS Single-Code Coupling This chapter describes the ANSYS Multi-field solver- single code (MFS), available for a large class of coupled analysis problems. An automated tool for solving sequentially coupled field problems, the ANSYS Multi-field solversupersedes the physics file-based procedure and provides a robust, accurate, and easy to use tool for solving sequentially coupled physics problems. It is built on the premise that each physics is created as a field with an independent solid model and mesh. You can identify surfaces or volumes for coupled load transfer, and then use a set of multi-field solver commands to configure the problem and define the solution sequencing. The solver automatically transfers coupled loads across dissimilar meshes. The MFS solver is applicable to static, harmonic, and transient analysis, depending on the physics requirements. Any number of fields can be solved in a sequential (staggered) manner. The ANSYS Multi-field solver is one of two versions of the multi-field solver (see Chapter 4, “Multi-field Analysis Using Code Coupling” for a description of the other version, the MFX solver). The MFS solver is the basic multi- field solver used if the simulation involves small models that have all physics field contained within a single program (e.g., ANSYS). The MFS solver uses iterative coupling where each physics is solved sequentially and each matrix equation solved separately. The solver iterates between each physics field until the loads transferred across physics interfaces converge. The ANSYS Multi-field solver has the following main features: • Each physics is created as a "field" with an independent model and mesh. • Each field is defined by a group of element types. • Load transfer regions are identified by surfaces and/or volumes. • Load vector coupling occurs between fields. • Each field may have different analysis types. • Each field may have different solvers and analysis options. • Each field may have a different mesh discretization. • Surface load transfer can occur across fields. • Volumetric load transfer can occur across fields. • Non-structural elements can be automatically morphed. • Independent results files are created for each field. The ANSYS Multi-field solver can solve a large class of coupled field problems. Typical applications include the following: • Thermal stress • Joule heating • Induction heating and stirring • Fluid-structure interaction • Electromagnetic-structural interaction • Electrostatic-structural interaction • RF heating ANSYS Coupled-Field Analysis Guide . ANSYS Release 10.0 . 002184 . © SAS IP, Inc. • Current conduction-magnetostatics The following ANSYS Multi-field solver (MFS) topics are available: 3.1. The ANSYS Multi-field solver and Solution Algorithm 3.2. ANSYS Multi-field solver Solution Procedure 3.3. Sample Thermal-Stress Analysis of a Thick-walled Cylinder (Batch or Command Method) 3.4. Sample Electrostatic Actuated Beam Analysis (Batch or Command Method) 3.5. Sample Induction-Heating Analysis of a Circular Billet 3.1. The ANSYS Multi-field solver and Solution Algorithm The ANSYS Multi-field solver is available in the ANSYS Multiphysics product. It provides you with the ability to solve coupled-field problems such as the following: • MEMS Actuation (electrostatic/structural without fluid coupling) • Electric Machines (magneto/thermal/structural coupling) • Joule Heating (thermal/electric/structural coupling) • Induction Heating (harmonic electromagnetic/thermal coupling) • Induction Stirring (harmonic electromagnetic/thermal/fluid coupling) • RF Heating (high-frequency electromagnetic/thermal/structural coupling) • Thermal/Stress Analysis (thermal/structural coupling) • Fluid Solid Interaction Analysis (fluid/structural coupling) The following ANSYS Multi-field solver algorithm topics are available: 3.1.1. Load Transfer 3.1.2. Mapping 3.1.3. Coupled Field Loads 3.1.4. Elements Supported 3.1.5. Solution Algorithm 3.1.1. Load Transfer Load transfer is the process by which one field transmits mesh-based quantities to another field. The transfers occur from a surface to a surface or from a volume to a volume. Electrostatic Actuated Beam Analysis is an example of a surface load transfer problem. In that problem, forces are transmitted from the electrostatic field to the structural field and displacements are transmitted from the structural domain to the electrostatic field. Thermal- Stress Analysis of a Thick-walled Cylinder and Induction-heating Analysis of a Circular Billet are examples of volumetric load transfer problems. In the thick-walled cylinder problem, temperatures are transferred from the thermal field to the structural field. In the circular billet problem, heat generation is transferred from the magnetic field to the thermal field and temperatures are transferred from the thermal field to the magnetic field. The ANSYS Multi-field solver automatically transfers coupled loads across dissimilar meshes. Two interpolation methods are available for a load transfer: profile preserving and globally conservative. In a profile preserving interpolation, each node on the receiver side maps onto an element on the sender side (α i ). The transfer variable is then interpolated at α i . The transfer value is T i = φ (α i ). Thus, all nodes on the receiver side query the sender side. Chapter 3: The ANSYS Multi-field (TM) Solver - MFS Single-Code Coupling ANSYS Coupled-Field Analysis Guide . ANSYS Release 10.0 . 002184 . © SAS IP, Inc. 3–2 Figure 3.1 Profile Preserving Interpolation α α α α α In a globally conservative interpolation, each node X on the sender maps onto an element on the receiver side. Thus, the transfer variable on the sender is split into two quantities that are added to the receiver nodes. As shown in the following figure, the force at node 4 splits into forces at nodes 3' and 4'. Figure 3.2 Globally Conservative Interpolation β β β β β β β Some important points to remember about the interpolation methods are: • For a profile preserving interpolation, the forces and heat rate will not balance on this interface. For a globally conservative interpolation, total force and total heat rate will balance on this interface. However, locally the distributions might not agree. Section 3.1: The ANSYS Multi-field solver and Solution Algorithm 3–3 ANSYS Coupled-Field Analysis Guide . ANSYS Release 10.0 . 002184 . © SAS IP, Inc. Figure 3.3 Profile Preserving Interpolation - Load Imbalances ∫ ∫ ≠ Figure 3.4 Globally Conservative Interpolation - Load Balance ∫ ∫ = • It makes physical sense to conserve quantities like heat flux and force at the surface interfaces. Similarly, heat generation should be conserved at volumetric interfaces. However, it does not make physical sense to conserve displacements or temperatures on a integral basis. However, displacement and temperature profiles should be adequately captured across interfaces. • As shown in the following figures, for a profile preserving interpolation, you should have a coarse mesh on the sending side and a fine mesh on the receiver side, rather than the converse. When the coarse mesh is on the sending side, the receiver adequately captures the normal heat flux profile. On the receiver side, a fine mesh ensures a sufficient number of nodes. When the coarse mesh is on the receiver side, the re- ceiver does not adequately capture the normal heat flux profile due to an insufficient number of nodes on the receiver side. Chapter 3: The ANSYS Multi-field (TM) Solver - MFS Single-Code Coupling ANSYS Coupled-Field Analysis Guide . ANSYS Release 10.0 . 002184 . © SAS IP, Inc. 3–4 Figure 3.5 Profile Preserving Interpolation - Coarse Mesh on the Sending Side Figure 3.6 Profile Preserving Interpolation - Coarse Mesh on the Receiver Side • As shown in the following figures, for a globally conservative interpolation it is better to have a fine mesh on the sending side and a coarse mesh on the receiver side than the converse. When the fine mesh is on the sending side, the receiver adequately captures the forces. When the fine mesh is on the receiver side, the load distribution on the receiver might not be captured, even though the total force on the receiver is equal to the total force on the sender. Section 3.1: The ANSYS Multi-field solver and Solution Algorithm 3–5 ANSYS Coupled-Field Analysis Guide . ANSYS Release 10.0 . 002184 . © SAS IP, Inc. Figure 3.7 Globally Conservative Interpolation - Fine Mesh on Sending Side Figure 3.8 Globally Conservative Interpolation - Fine Mesh on Receiver Side • The above two points hold true if either the sender or receiver mesh is made of higher order elements. Exercise care if you wish to produce a node-to-node mapping from higher order elements to lower order elements. For example, as shown in the following figure, a globally conservative load transfer across an interface that has the same number of elements on both sides will not produce the correct profile if the receiver is higher order. Figure 3.9 Three Lower Order Elements To get the right profile, you need to double the number of sending lower order elements as shown in the following figure. Also note you cannot drop mid-side nodes at a surface or volume interface. Chapter 3: The ANSYS Multi-field (TM) Solver - MFS Single-Code Coupling ANSYS Coupled-Field Analysis Guide . ANSYS Release 10.0 . 002184 . © SAS IP, Inc. 3–6 Figure 3.10 Six Lower Order Elements • You can specify a globally conservative or a profile preserving interpolation method for forces, heat flux, and heat generation. Displacement and temperature transfers are always profile preserving. 3.1.2. Mapping In order to transfer loads across a dissimilar mesh interface, the nodes of one mesh must be mapped to the local coordinates of an element in the other mesh. The MFS solution algorithm must perform two mappings for every surface to surface and volume to volume interface. For example, in a fluid-solid interaction problem, fluid nodes must be mapped to the solid elements to transfer displacements. Likewise, solid nodes must be mapped to the fluid elements to transfer stresses. Figure 3.11 Fluid-Solid Interaction Load Transfer 3.1.2.1. Mapping Algorithms There are two mapping algorithms available: global and bucket search. Global Method As the name implies, the node in question loops over all the existing elements of the other mesh and tries to locate an element that it can be mapped to. Most nodes find a unique element and are mapped easily. However, occasionally a node is mapped to two or more elements. This occurs when a finite nonzero gap/penetration exists Section 3.1: The ANSYS Multi-field solver and Solution Algorithm 3–7 ANSYS Coupled-Field Analysis Guide . ANSYS Release 10.0 . 002184 . © SAS IP, Inc. [...]... field solution ANSYS Coupled-Field Analysis Guide ANSYS Release 10.0 002184 © SAS IP, Inc 3 13 Chapter 3: The ANSYS Multi-field (TM) Solver - MFS Single-Code Coupling 3. 2 ANSYS Multi-field solver Solution Procedure The procedure for doing an MFS solution analysis consist of the following steps: 3. 2.1 Set up Field Models 3. 2.2 Flag Field Interface Conditions 3. 2 .3 Set up Field Solutions 3. 2.4 Obtain... required to solve a particular field, including mesh, boundary conditions, analysis options, output options, etc For information on how to set up a field analysis, refer to the ANSYS Fluids Analysis Guide, the ANSYS Structural Analysis Guide, the ANSYS Thermal Analysis Guide, and the ANSYS Low-Frequency Electromagnetic Analysis Guide If you will be generating radiosity surface elements (RSURF), you must... interface between the structural field and the non-structural field 3 22 ANSYS Coupled-Field Analysis Guide ANSYS Release 10.0 002184 © SAS IP, Inc Section 3. 3: Sample Thermal-Stress Analysis of a Thick-walled Cylinder (Batch or Command Method) 3. 3 Sample Thermal-Stress Analysis of a Thick-walled Cylinder (Batch or Command Method) 3. 3.1 Problem Description A thick-walled cylinder is maintained at... [1] Coupled-Field Elements PLANE SOLID PLANE 13 SOLID5 PLANE67 SOLID62 PLANE2 23 SHELL SOLID69 3 12 SHELL157 ANSYS Coupled-Field Analysis Guide ANSYS Release 10.0 002184 © SAS IP, Inc Section 3. 1: The ANSYS Multi-field solver and Solution Algorithm Electromagnetic Elements SOLID98 PLANE226 PLANE227 1 You can use the FLOTRAN remeshing capability in a fluid-solid interaction analysis See Section 7 .3: ... step size for each field analysis ANSYS Coupled-Field Analysis Guide ANSYS Release 10.0 002184 © SAS IP, Inc 3 19 Chapter 3: The ANSYS Multi-field (TM) Solver - MFS Single-Code Coupling Figure 3. 18 Time Steps ¡ ¤ W QV URS VR I U QT P ¤ ©¨¦ § ¤ ¡ ¥£ ¢ IT #H ¡GED&&5¤ ¦ 8 A ¤ ¤ F ¤ CB " 4 © 4#" ¡8 § ¥¥" ¡8 § 9 %¦ 7 @ 8 4#7 § 615¤ '! ¤ 3 " ¤ £ 4 # 3 © 21 ¤ ¡ 4 " 0 ¡... the MFS analysis, use a relaxation value of 1.0 for all quantities The default relaxation value is 0.5 3 18 ANSYS Coupled-Field Analysis Guide ANSYS Release 10.0 002184 © SAS IP, Inc Section 3. 2: ANSYS Multi-field solver Solution Procedure 3. 2 .3. 5 Set up Time and Frequency Controls The following table lists the steps to set up the time and frequency controls Step Command Set end time for MFS analysis. .. SOLID95 BEAM188 SHELL 93 PLANE182 SOLID185 BEAM189 SHELL181 PLANE1 83 SOLID186 SOLSH190 SOLID187 Thermal Elements PLANE SOLID PLANE35 SOLID70 PLANE55 SOLID87 PLANE77 SHELL SHELL57 SOLID90 Table 3. 3 Electromagnetic, Fluid, and Coupled-Field Elements Electromagnetic Elements PLANE SOLID HF PLANE 53 SOLID96 HF119 PLANE121 SOLID97 HF120 PLANE 230 SOLID117 SOLID122 SOLID1 23 SOLID 231 SOLID 232 Fluid Elements PLANE... (MFVOLUME) Analysis options are set for the thermal solution and written to a command file (MFCMMAND) Similarly, analysis options are set for the structural solution and written to a command file The solution is then performed The following figure illustrates the thermal and structural mesh ANSYS Coupled-Field Analysis Guide ANSYS Release 10.0 002184 © SAS IP, Inc 3 23 Chapter 3: The ANSYS Multi-field... solution of the MFS analysis ANSYS Coupled-Field Analysis Guide ANSYS Release 10.0 002184 © SAS IP, Inc 3 17 Chapter 3: The ANSYS Multi-field (TM) Solver - MFS Single-Code Coupling You can define an external field (MFEXTER) that predefines loads and exists only to transfer those loads to another field It requires fully specified loads and does not perform a solution during an MFS analysis It only transfers... the ANSYS Commands Reference for more information about this command 3. 1 .3 Coupled Field Loads The following tables show the loads that the ANSYS Multi-field solver can transfer in a coupled physics analysis Table 3. 1 Load Transfer Between Fields Field Structural Structural Thermal Electric Magnetic Fluid 1 2 3 4 5 6 7 Thermal Electric Magnetic 8 Fluid 1 3 10 Structural - Thermal Coupling ANSYS Coupled-Field . not agree. Section 3. 1: The ANSYS Multi-field solver and Solution Algorithm 3 3 ANSYS Coupled-Field Analysis Guide . ANSYS Release 10.0 . 002184 . © SAS IP, Inc. Figure 3. 3 Profile Preserving. field solution. Section 3. 1: The ANSYS Multi-field solver and Solution Algorithm 3 13 ANSYS Coupled-Field Analysis Guide . ANSYS Release 10.0 . 002184 . © SAS IP, Inc. 3. 2. ANSYS Multi-field solver. Transfer —Forces Send Forces— Receive Section 3. 1: The ANSYS Multi-field solver and Solution Algorithm 3 11 ANSYS Coupled-Field Analysis Guide . ANSYS Release 10.0 . 002184 . © SAS IP, Inc. 3. 1.4. Elements Supported The ANSYS Multi-field