CAE simulations. The art of the possible.

What factors contribute to making CAE projects successful? In the company I work for, in 15 years, we have delivered hundreds of CAE projects to industrial companies (most of them in the turbomachinery field). Some projects were highly successful, while others were not. In this article, I would like to share a few thoughts and lessons learned about project-success patterns and engineering productivity in general.

The Game

In engineering, we don’t simulate reality. We merely simulate our understanding of reality with currently available resources. In other words, the game we play here is about turning our knowledge and effort (and talent) into the best possible results. CAE projects, like software, are never really finished. They only have their versions. At any point, you can make them better. When chasing accuracy, the effort grows exponentially, so it’s smart to recognize the point when the results are good enough. Having clear, measurable goals is critical to prevent infinite drift, resource waste, and disappointment. Well-defined goals help to navigate, focus, and prioritize. The game we play is all about goals and their feasibility with the available knowledge and effort.

Continue reading on CFD SUPPORT website >>> https://www.cfdsupport.com/cae-simulations-the-art-of-the-possible/

Hi contributors,

I sincerely appreciate your team's efforts in making your work publicly available online—it has been immensely helpful for OpenFOAM users and developers alike. After reading your article (Node266 - CFD SUPPORT), I followed the provided instructions to configure OpenFOAM to generate a cellZone using snappyHexMesh.

Unfortunately, the attempt was unsuccessful. The number of cells in both the cellZone and faceZones files turned out to be zero, and checkMesh.log confirms this issue. When I check the result via paraFoam, I also find that net0 ~ net4 contain no mesh—they are empty. This is not only contrary to my expectations, but also differs from the result described in the article.

I am using OpenFOAM v2012, and the net0 section in my snappyHexMeshDict was set up following the example from your webpage.

I’ve uploaded the relevant case below. I would greatly appreciate any guidance.

--------------------------------------------------------------------------------------------------

snappyhexmeshdict:

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  v2012                                 |
|   \\  /    A nd           | Website:  www.openfoam.com                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    object      snappyHexMeshDict;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
#include "../varsSettings" //Include global variables
castellatedMesh true;
snap            true;
addLayers       false;//true;
geometry
{
    floater
    {
        type 	triSurfaceMesh;
        file 	"DeepCwindPlatform_heave.stl";
    }
    
    net1
    {
        type 	triSurfaceMesh;
        file 	"Net1_improved_heave.stl";
    }
    
    net2
    {
        type 	triSurfaceMesh;
        file 	"Net2_improved_heave.stl";
    }
    
    net3
    {
        type 	triSurfaceMesh;
        file 	"Net3_improved_heave.stl";
    }
    
    net4
    {
        type 	triSurfaceMesh;
        file 	"Net4_improved_heave.stl";
    }
    
    net0
    {
    	type	searchableBox;
    	min		(-100	-50	-120);
    	max		(100	50	-80);
    }
    
    refineFreeSurface_L1
    {
        type searchableBox;
        min ($minX  $minY -10);
        max ($maxX  $maxY  10); 
    }
    
    refineFreeSurface_L2
    {
        type searchableBox;
        min (#calc "$minX+$inLen+20"  -70 -8);
        max (#calc "$maxX-$outLen-20"  70  8); 
    }
    
    refineFloater_L1
    {
        type searchableBox;
        min (-51  -49	#calc "-30 + $decay_z + $offset_z");
        max ( 37   49 	#calc "22 + $decay_z + $offset_z"); 
    }
};
castellatedMeshControls
{
    maxLocalCells 100000;
    maxGlobalCells 2000000;
    minRefinementCells 0;
    maxLoadUnbalance 0.10;
    nCellsBetweenLevels 1;
    features
    (
        {
        	file    "DeepCwindPlatform_heave.eMesh";
            level   4;
        }
        
		{
        	file	"Net1_improved_heave.eMesh";
        	level	4;
		}
		
		{
        	file	"Net2_improved_heave.eMesh";
        	level	4;
		}
		
		{
        	file	"Net3_improved_heave.eMesh";
        	level	4;
		}
		
		{
        	file	"Net4_improved_heave.eMesh";
        	level	4;
		}
    );
    refinementSurfaces
    {
		floater
		{
			level (4 4);//(5 5);
			patchInfo
        	{
          		type wall;
 
          		// Optional group
          		// inGroups (meshedWalls);
        	}
		}
          
		net1
    	{
			level (4 4);
			cellZone net1Zone;
/*			cellZoneInside inside;*/
			faceZones net1fZone;
    	}
    	net2
    	{
        	level (4 4);
			cellZone net2Zone;
/*			cellZoneInside inside;*/
			faceZones net2fZone;
    	}
    	net3
    	{
        	level (4 4);
			cellZone net3Zone;
/*			cellZoneInside inside;*/
			faceZones net3fZone;
		}
    	net4
    	{
        	level (4 4);
			cellZone net4Zone;
/*			cellZoneInside inside;*/
			faceZones net4fZone;
    	}
    	
    	net0
    	{
        	level (4 4);
			cellZone net0Zone;
/*			cellZoneInside inside;*/
			faceZones net0fZone;
    	}
    }
    resolveFeatureAngle 45;//30;
    planarAngle 30;
    refinementRegions
    {
        refineFreeSurface_L1
        {
            mode inside;
            levels ((1e-5 1)); //First entry here is distance, which will be ignored unless mode = distance
        }
        
        refineFreeSurface_L2
        {
            mode inside;
            levels ((1e-5 2)); //First entry here is distance, which will be ignored unless mode = distance
        }
        
        refineFloater_L1
        {
            mode inside;
            levels ((1e-5 2)); //First entry here is distance, which will be ignored unless mode = distance
        }
        
/*        net1*/
/*        {*/
/*            mode inside;*/
/*            levels ((1e-5 3));  // STL 内部 refinement 到 level 4*/
/*        }*/
/*        net2*/
/*        {*/
/*            mode inside;*/
/*            levels ((1e-5 3));*/
/*        }*/
/*        net3*/
/*        {*/
/*            mode inside;*/
/*            levels ((1e-5 3));*/
/*        }*/
/*        net4*/
/*        {*/
/*            mode inside;*/
/*            levels ((1e-5 3));*/
/*        }*/
    }
    limitRegions
    {
    }
        locationInMesh (-150 0 0);
        allowFreeStandingZoneFaces true;//false;
        faceZoneControls
        {
        }
    locationsOutsideMesh ((100 100 100));
}
snapControls
{
    nSmoothPatch 5;//3
    tolerance 2.0;
    nSolveIter 50;//30;
    nRelaxIter 10;//5;
        nFeatureSnapIter 20;//10;
        implicitFeatureSnap false;//true;
        explicitFeatureSnap true;//false;
        multiRegionFeatureSnap false;
}
addLayersControls
{
    relativeSizes true;
        expansionRatio 1.25;
        finalLayerThickness 0.64;
    	minThickness 0.1;
    layers
    {
		floater
		{
			nSurfaceLayers    2;//3;
		}
    }
    nGrow 0;
        featureAngle 180;//180;
        maxFaceThicknessRatio 0.5;//0.5;
        nSmoothSurfaceNormals 1;
        nSmoothThickness 10;
        minMedialAxisAngle 90;
        maxThicknessToMedialRatio 0.3;
        nSmoothNormals 3;
        slipFeatureAngle 30;
        nRelaxIter 5;
        nBufferCellsNoExtrude 0;
        nLayerIter 50;
        nRelaxedIter 20;
}
meshQualityControls
{
    #include "meshQualityDict"
    relaxed
    {
        maxNonOrtho 75;
    }
        nSmoothScale 4;
        errorReduction 0.75;
}
mergeTolerance 1e-6;
// ************************************************************************* //

Thank you very much in advance!

Best regards,

Liu Jiaming

Hi,

I have a problem with report at the end?

Program made all 3000 iteration ( about 1.200.000 pcs), but at the end is allways problem with the report: (see picture below).

Thanks.

Hi,

I have a problem with report at the end?

Program made all 3000 iteration ( about 1.200.000 pcs), but at the end is allways problem with the report: (see picture below).

Thanks.

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I have just installed v24.10 of TCAE-Lite. Initially I installed under Linux, sicne that is where I would really like to use the software. Having downloaded the pipe tutorial I load the case and get this message "Project configuration not fully valid according to TCAE-Lite 24.10 and may have been auto-corrected." When I try to run, I get a message that the caluclation cannot be started, and that the project contains some problems. Upon using the check option, it says that there is no geometry loaded for solid component 1. The stl file does exist in commonData\TMESH\imported and I can load it into ParaView with no issues.

So I then tried installing under Windows. In this case it does not complain about the geometry. However, when I try to run I still get a failure, which is "Failed to execute "netgenSTLMesh" (error 2)." It asks me to check an error log (mesh-err-07-netgenMesh-component1.log), but this file does not exist (there is no netgenmesh log file, and the mesh-err-07 file is called mesh-err-07-mergeMultiMeshes.log.

Can anyone provide details as to why the FEA meshing fails under Windows, and why the geometry does not work under Linux?

Hi Foamers, 

Based on the given instructions underneath, I have been able to come up with this design. Could you help confirm if the attached image to this topic looks promising or requires some modifications? Thanks 😊 

“Introduction

Finishing a small meshing task is the first possibility multi-block mesh using the blockMesh utility or Salome,

e. The task, creation of a small

Geometry

wall

outlet

cut

inlet

Z

Parameters d=50.8 mm

I=508 mm a=12.7 mm

= a/2

Description

The geometry represents half of the 2" pipe inner volume. It is composed of four building blocks. The first block (No. 1) represents the core of the pipe. The other blocks (No. 2, 3, and 4) fill the outside pipe volume.

The mesh blocks must be split by more than one cell in every direction. You can select how many cells you want to use. Apply the mesh grading, if possible.

The outside volume surfaces are called inlet, outlet, wall, and cut. Select an appropriate patch type for each surface.

The blockMesh utility writes out a log. Ensure no errors are reported.

Hint: The local coordinate system in each block should be aligned with the global coordinate system!”

I would like to report an issues with SnappyHexMesh when running with OpenFoam v2306. I'm currently try to run SnappyHexMesh with high mesh number structure in HPC cloud environment. Unfortunately, the process of "snappyhexmesh -overwrite" stuck and hanging at refinement phase with message "Found point (-0.001 0.0015 0.0015) in cell 40402 on processor 0". I did run this on serial processing method with VM specification 44vCPU and 315GiB of memory. I already try to run over parallels processing but it's same. Below are sequences of steps I did run and produce the message. Mesh number are define by "blockMeshDict". From my observation, this happens when I'm running with higher mesh number but if I'm lowering the number the process works fine. 

Running steps:

foamCleanPolyMesh

blockMesh

topoSet

createPatch -overwrite

surfaceFeatureExtract

# Run snappyHexMesh before decomposition

snappyHexMesh -overwrite << this steps produce the hanging process.

Hey everyone,

I’m working on a harmonic analysis simulation and have a question about splitting the frequency range.

Let’s say the frequency range I’m analyzing is from 10 Hz to 100 Hz. Instead of running the harmonic simulation for the entire range in one go, is it feasible to split the range into smaller intervals, for example:

• One simulation for 10-50 Hz, and

• Another for 50-100 Hz?

I’m trying to understand if this approach would still provide accurate results or if there are any drawbacks, particularly at the boundaries where the ranges are split. Has anyone used this method in their analysis, and if so, were there any issues with accuracy or continuity?

From my understanding, harmonic analysis calculates the steady-state response at a specific frequency. For example, consider the system at 10 Hz, assuming no damping. We know the equation is:

M(x′′)+k(x)=Fsin⁡(ωt)M(x'') + k(x) = F \sin(\omega t)M(x′′)+k(x)=Fsin(ωt)

Since 10 Hz is the starting frequency, the initial displacement at all nodes would be zero, x(t)=0x(t) = 0x(t)=0. By solving this, we get the response for this frequency.

Now, when the solver moves to 11 Hz, will it assume the initial displacement is zero again, or will it consider the solution from the previous frequency?

I’d appreciate any insights or suggestions regarding the feasibility of splitting the frequency range and how solvers handle initial conditions between different frequencies.

This is more like an open question than a fully formed topic with both question and answer.

I am running an incompressible laminar flow simulation with the pimpleFoam solver. It has two openings on one side (n1 and n2) and one on the other (n3). I have set up the pressure boundary conditions so that the flow is driven primarily by the pressure applied at n3. The flow should be changing direction halfway. Realistically, the total volume passing through an opening should be the same for the two flow direction. Yet, when I sum over the patch flow rates (postProcessing function) of the two flow directions and compare them, they are different. What could be the potential reason(s) for this phenomenon?

Following is the pressure boundary condition I set up:

/*--------------------------------*- C++ -*----------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     | Website:  https://openfoam.org
    \\  /    A nd           | Version:  10
     \\/     M anipulation  |
\*---------------------------------------------------------------------------*/

FoamFile
{
    version     2.0;
    format      ascii;
    class       volScalarField;
    object      p;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [0 2 -2 0 0 0 0];

internalField   uniform 0;

boundaryField
{
    n1
	{
		type            totalPressure;
		p0              uniform 0;  // Reference total pressure (e.g., atmospheric pressure in Pascals)
		U               U;               // Velocity field name
		phi             phi;             // Flux field name
		rho             none;            // Density, use 'none' for incompressible flow
		psi             none;            // Compressibility, use 'none' for incompressible flow
		gamma           1;               // For incompressible flow, use 1
	}

	n2
	{
		type            totalPressure;
		p0              uniform 0;  // Reference total pressure
		U               U;
		phi             phi;
		rho             none;
		psi             none;
		gamma           1;
	}


    n3
    {
		type		uniformTotalPressure;
	p0
	{
		type		sine;
		frequency	0.3333333333333333;
		amplitude	-50.0;
		level		0;
	}


    }
    walls
    {
        type            zeroGradient;
    }

    defaultFaces
    {
        type            empty;
    }

}

// ************************************************************************* //



New TCAE 24.03 Release

We're happy to announce the release of the latest version of TCAE simulation software - Version 24.03! 

TCAE continues to be the go-to solution for engineers seeking powerful, user-friendly, and cost-efficient simulation software that can tackle complex engineering challenges with ease.

To introduce you to the exciting features of the new TCAE 24.03, we invite you to join our upcoming webinar. Here are the details:

Title: TCAE 24.03 Introduction

Date: Thu, Apr 11, 2024 

Time: 3:00 PM CEST

Duration: Approximately 1 hour

Agenda:

Overview of TCAE Version 24.03. Live demonstration showcasing the user-friendly interface, advanced features, and fast solvers 

Q&A Session: 

Ask your questions, and our experts will provide answers. Feel free to send your questions in advance to info@cfdsupport.com.

Speakers:

🎤 Lubos Pirkl, Co-Founder at CFD Support 

🛠️ Radek Máca, Head Engineer at CFD Support

Registration: 

Secure your spot now by registering at https://attendee.gotowebinar.com/register/6791084528975214686

Even if you can't attend the live event, register anyway to receive the recording for future viewing at your convenience.

More Information: 

Visit our website to learn more about TCAE and its capabilities: https://www.cfdsupport.com/tcae.html. Explore our publishable benchmarks and real project-based case studies, all of which are transparent and freely downloadable.

With TCAE, you not only gain access to cutting-edge simulation technology but also become a valued member of our community. Benefit from our ongoing support, training resources, and valuable insights to elevate your engineering projects.

Don't miss this opportunity to discover how TCAE Version 24.03 can empower you to overcome your engineering challenges and achieve your design goals.

We look forward to welcoming you to the webinar!

As always. We're one email away!

Best Regards, 

CFD SUPPORT Team

Airfoil Acoustic Benchmark NACA 0012

We are thrilled to announce the launch of our newest engineering simulation benchmark Airfoil Acoustic Benchmark NACA 0012, showcasing the capabilities of our cutting-edge simulation software, TCAE. This benchmark, centered around the NACA 0012 airfoil, delves into the realm of Computational Aero-Acoustics (CAA) and highlights the smooth usability and advanced features of TCAE software.

Access the Airfoil Acoustic Benchmark NACA 0012 case study: To learn more about this benchmark and dive into the details of our study, please visit our website. You'll find comprehensive documentation, detailed results, and insights into the fascinating world of CAA.

Experience the flowing air and vortices around the NACA0012 airfoil firsthand by watching our accompanying YouTube video: https://youtu.be/6mKSCT1-wK4

This video offers a glimpse into the intricate dynamics captured in our simulations including the sound reconstruction!

Join Our Webinar on March 5, 2024: We invite you to join our upcoming webinar where we'll delve deeper into the methodology, results, and implications of this benchmark study. Register now to secure your spot and engage with our team of experts:  https://attendee.gotowebinar.com/register/6369598840280329815

Download the project and run it for yourself: For those eager to explore the project firsthand, the entire benchmark project is available for download on our website. Simply visit our website to access the files and replicate the study in your own environment. 

https://www.cfdsupport.com/naca-0012-acoustic-benchmark.html​​

Thank you for your continued support and interest in our engineering simulation endeavors. We are excited to share this milestone with you and look forward to your participation in our upcoming webinar.

Stay tuned for more exciting updates on the horizon. Together, we'll shape the future of simulation.

As always. We're one email away!

Best Regards, 

CFD SUPPORT Team

Hi everyone

I´m trying to create another equation of state model based on Bussinesq, but when i write "wmake" the next set of errors and warnings are printed in the terminal of OF4Win 20.09:

Can you please give me some help with this problem? Thanks in advance

I am using OpenFoam 20.9 for Windows 10.When i run the motorBike tutorial - no problem .If i use my own stl file which i have used many times on all OpenFoam platforms i get the error u will see in attached file. Once decomposePar has run going to snappyHexMesh those errors show. Also when simulation run the stl file lOpenFOAM for Windows 20.09 (v2)