Results analysis - Recent Threads

How to model chiller part-load in CFD with hot standby units?

AK202512115130 — Sat, 13 Dec 2025 15:13:35 GMT

Hi everyone, I’m using Cadence Reality DC Advanced to simulate an air-cooled chiller plant. The building load is capped at 80%, and all chillers (including standby) are running to share that load.
Questions:

Represent part-load heat rejection at condenser coils?
Model fan speed control when the software uses chilled water supply temperature as the control basis?
Any best practices for distributing load across multiple chillers in this scenario?

Looking for tips or workflows—thanks!

RE: How to model chiller part-load in CFD with hot standby units?

FR20251216246 — Tue, 16 Dec 2025 17:35:19 GMT

Hi,

Fan speed control can be implemented on the chiller by setting the Airflow > Flow Option to Controlled. This exposes an extra set of properties in a Controls section, and creates a Controller and Sensor as a child of the Chiller. The Sensor is automatically set to the Coolant Supply Temperature.

For part-load scenarios, I would recommend submitting a case through the ASK portal, where we can provide specific advice based on the input data you have for the chiller. You can do this at support.cadence.com

Developing Integrals at Rotor-Stator Interfaces: A Python API Document for Fidelity Platform

Gaurav — Tue, 07 Oct 2025 07:44:47 GMT

This script is designed to generate integral values at the critical rotor-stator (RS) interface with high efficiency. The resulting data is recorded in a CSV file, enabling easy access and in-depth analysis. The primary goal of this script is to facilitate the creation of integrals, providing users with valuable insights for their projects.

To initiate the process, execute the main script file, `Axial_Turbine_Aachen_2025.1.py`. This will create a project directory in the same location as the script file. Within this directory, a `project.fidelity` file will be generated.

To proceed, users must configure the postprocessing script file, `Post_Proc_Integral_RS_Interface.py`, by:

1. Assigning the project directory path to the `project_path` variable.
2. Designating a suitable path for storing desired integral values to the `image_path` variable.

By following these steps, users can successfully run the script file and obtain meaningful integral data:

1. Execute the main script file, `Axial_Turbine_Aachen_2025.1.py`.
2. Configure the `project_path` variable in the postprocessing script file.
3. Specify the `image_path` variable for storing integral values.
4. Run the postprocessing script file to generate integral values at the RS interface.
5. Access and analyze the resulting data in the CSV file.

https://support.cadence.com/apex/ArticleAttachmentPortal?id=a1OPP000001qiHJ2AY&pageName=ArticleContent

Transient

DC202411077358 — Tue, 23 Sep 2025 12:03:19 GMT

Parameters considered to calculate the Data Hall Transient, ACU response time and simulation time basically take into account which factors?

RE: Transient

Gaurav — Fri, 26 Sep 2025 09:56:19 GMT

In regards to calculating the Data Hall Transient, ACU response time, and simulation time, several key factors are taken into consideration. These include:

1. Heat load, which directly affects the overall thermal performance of the system.
2. ACU supply and return temperatures, which influence the cooling capacity and efficiency.
3. The volume of the room, which impacts airflow and heat distribution.
4. Thermal inertia of components such as IT equipment and the ACU itself, which can affect the system's response to temperature changes.
5. ACU control parameters, including temperature setpoints and dead bands, which dictate the system's temperature control strategy.
6. Simulation time and time step size, which determine the precision and duration of our simulations.
7. Air flow requirements, which are critical for maintaining a stable and efficient cooling environment.

Please note that these factors may not be exhaustive, and we may need to adjust parameters such as the gain scaling factor value based on our simulations. If you have any further questions or concerns, please don't hesitate to let out know.

Creating Spanwise Visualizations with Derived Quantities using Python Scripting

Gaurav — Mon, 08 Sep 2025 14:08:34 GMT

This application note presents a step-by-step tutorial on generating a spanwise plot from derived quantities within a result analysis setup in Fidelity version 2025; it uses a script-based methodology.

This script file aims to generate a spanwise plot from derived quantities. The script is structured into three main parts to achieve this objective.

The first part details the creation of derived quantities, a crucial step that lays the groundwork for the subsequent sections.

The second part focuses on generating a spanwise plot for a specific domain using the previously created derived quantities and provides guidance on how to tailor the plot to meet specific requirements.

The final part explains the process of exporting the generated image from the Fidelity GUI, with Fidelity Python functions employed throughout to ensure smooth execution.

Creating Spanwise Visualizations with Derived Quantities using Python Scripting

A Step-By-Step Guide for Developing Blade-to-Blade (B2B) Surface Integrals in Fidelity Platform Using Python API Functions

Gaurav — Thu, 28 Aug 2025 06:41:57 GMT

We are excited to share a script-based method for efficiently generating integrals in Fidelity version 2025.1, utilizing the Axial Turbine Aachen setup as a demonstration case. This application note serves as a comprehensive guide, providing a step-by-step walkthrough for creating a custom script file tailored to your specific needs.

Primary Objective

The script's primary objective is to automate the process of generating integrals on the B2B surface at desired span locations, compute integral values, and store the results in a convenient ".csv" file format. By leveraging this automation, Fidelity users can efficiently extract multiple values at various locations, thereby significantly reducing the time and effort required for manual calculations.

Downloadable Script Files

To facilitate the implementation of this script-based approach, we are providing two downloadable script files:

1. Axial_Turbine_Aachen_2025.1.py: This primary script is responsible for running simulations.
2. Post_Proc_Integral_B2B_Surface.py: This secondary script employs Python functions to generate integrals.

These scripts can be easily integrated into your Fidelity workflow, enabling you to efficiently generate integrals and analyze results. We invite you to explore this script-based method and experience the benefits of streamlined calculations and increased productivity.

You can access the downloadable script files and explore the detailed step-by-step guide in this application note. We welcome your feedback and look forward to your participation in the discussion forum.

A Step-By-Step Guide for Developing Blade-to-Blade (B2B) Surface Integrals in Fidelity Platform Using Python API Functions

Post processing LES vs RANS

LJ202505013133 — Thu, 01 May 2025 15:07:47 GMT

Which post processing tool is recommended for comparing LES (made using CharLES), RANS and wind tunnel oil flow visualization results to each other?

RE: Post processing LES vs RANS

Gaurav — Mon, 05 May 2025 07:29:36 GMT

Yes, Tecplot can function properly, but it depends on the amount of RAM you have available.

RE: Post processing LES vs RANS

LJ202505013133 — Fri, 02 May 2025 13:22:43 GMT

Many thanks.

Can Tecplot work well for > 1 billion cell mesh LES simulations?

RE: Post processing LES vs RANS

Gaurav — Fri, 02 May 2025 08:44:59 GMT

First, what data type do you need to compare the contour or line plots?
Second, for RANS simulation, which software are you using?

If you are using multiple simulation software, you can export the result file and utilize the Tecplot software.

Please go through the following link before making any comparisons.

Overview of DNS, LES, and RANS Turbulence Models

The discretization methods of LES and RANS differ. In LES, the governing equations are discretized using filters, which resolve large-scale turbulent eddies and model the smaller ones. However, in RANS, discretization is based on resolving the mean flow and modeling turbulent fluctuations.

RE: Cadence Reality/ 6sigmaRoom Thermal modelling Error

Thisisthenam — Sun, 12 Jan 2025 20:13:10 GMT

Thank you very much! Sorry for the late reply to this, but this was exactly what I needed thank you! Was so busy checking the ACU units I neglected to check each duct had an open vent on it, whoops.

Cadence Reality/ 6sigmaRoom Thermal modelling Error

Thisisthenam — Fri, 27 Dec 2024 03:05:12 GMT

Hello all, apologies if this is the wrong forum, I searched "Data Centre" and it lead here. Also apologies for occasionally using old Software names, still learning which package is now called what. If I am in the wrong area please point me to the correct forum if thats okay.

While running a Data Centre simulation I have come across the following error.

Background: I am running an updated Data Centre model, specifically I have added 8 new Air Cooling Units (ACU) to the .room model. These are as far as I can tell, identical to the existing units,.

Error: When I verify the model I get the critical error -> ThermalModellingError: More/Less flow is being supplied to the model than extracted (region number). I get multiples of this error with some saying More air some saying less air depending on the calculation region.

Tests I have done to find out more about the problem

1)Delete the new ACUs. Result: Mode now verifies fine

2)Delete 8 different ACUs and leave in the 8 new units. Result: Model throws same error as before.

3)Right Click ->Duplicate the New ACUs and delete the units I duplicated (leaving in the copies). Result: Model throws same error as before.

I also cannot seem to find any differences between these 8 ACUs and the others in the property tables for the units themselves and the Supply-Return vents.

Thanks in advance and sorry if this is in the wrong place.

RE: Cadence Reality/ 6sigmaRoom Thermal modelling Error

Gaurav — Mon, 06 Jan 2025 11:17:47 GMT

If you need further assistance, please register the case using the support.cadence.com website. There, you can also share your project directory with the case.

RE: Cadence Reality/ 6sigmaRoom Thermal modelling Error

Gaurav — Mon, 06 Jan 2025 11:01:58 GMT

This is a mass flow imbalance error. It is most likely because the ACUs are being added in a location where the supplies are contained inside a closed-off region. This could also be a result of a low-resolution grid, which may be creating a closed-off flow solution region.

The best way to diagnose this error would be to create a flow solution region. The way to do this would be to right-click on the Virtual Facility object in the model tree -> new -> flow solution region.

The property sheet of this object will most probably give more than one flow solution region.

One will be the primary one, which should contain most of the data hall, while the others will be much smaller and should most likely be around the cooling units. To solve the error, you must ensure that air can enter and exit those regions.

RE: Result of calculation in FineTurbo

Gaurav — Fri, 22 Dec 2023 17:01:08 GMT

Apologies for the delayed reply. I have conducted a simulation of Tutorial Number 5, which involves a 1.5-stage axial compressor with 2 stators and one rotor. I have maintained all settings as specified in the post, including a total pressure range of 119500–132500 Pa and the blade-to-blade surface at mid-span. However, I have not encountered any anomalous outcomes.

Result of calculation in FineTurbo

DenysK — Sun, 23 Jul 2023 10:06:05 GMT

Dear colleagues,
I deal with 3D calculation of axial compressor in FineTurbo. I have done steady state calculation.
I have encoutered with such issue. On the stator blade, on the suction side I have zone with increased Total Pressure.
It doesn't corresponds to written in books about aerodynamics of compressor. I atteched one picture and added values of parameter in different places of section of stator blade.

Perhaps, can someone explain this result or I did something incorrectly?

RE: Result of calculation in FineTurbo

DenysK — Thu, 03 Aug 2023 19:39:30 GMT

Dear Gaurav,

I am solving Tutorial No. 5 (1.5-stage axial compressor, 2 stators, and one rotor). I created mesh and set up of calculation according to documentation platform. I used Spalart Allmaras as turbulence model. I set initial conditions according to documentation.

In CFView I created a blade to blade surface at mid-span and selected Total Pressure. And result of these actions you can see in my previous reply.

If you have this documentation and .geomturbo files of 2 stators and 1 rotor, you can repeat these actions. After, in CFView you can create a blade to blade surface at mid-span, select Total Pressure and set range 119500 - 132500 Pa and you can see these strange result in domain of stator blade near suction side zone with increased Total Pressure.

Regards,

Denys

RE: Result of calculation in FineTurbo

Gaurav — Thu, 03 Aug 2023 07:41:53 GMT

Hi,

Please confirm that you are solving Tutorial No. 5 (1.5-stage axial compressor, 2 stators, and one rotor) or that you are solving another axial compressor configuration like a 2-stage or any other. Some points I am mentioning below need to be checked.

1. Check your machine's characteristics, like selecting the stator as a stator and not as a rotor.

2. Check your definition of rotating machinery.

3. Check your BCs and also which turbulence model you are using: a one-equation or two-equation model. If you are using the 2-equation model, then how are you calculating K and dissipation?

4. How you are setting your Initial conditions for turbomachinery, (Rotation direction).

5. Check whether you have modelled suction and pressure surfaces correctly.

Rgds,

Gaurav

RE: Result of calculation in FineTurbo

DenysK — Wed, 02 Aug 2023 20:38:37 GMT

Hello,
To continue our conversation. I did calculation according to TUTORIAL 5. MULTISTAGE AXIAL COMPRESSOR from documentation platform. For first calculation I set up Current Grid Level = <1 1 1>, for second calculation I set up Current Grid Level = <0 0 0>. When both calculations reached convergence I opened result of calculation in CFView and created a blade to blade surface at mid-span. I could see in domain of stator blade near suction side zone with increased Total Pressure.
Could someone explain this result of calculation?

RE: Regarding the calculation of KCS resistance

Benoit Mallol — Wed, 02 Aug 2023 12:35:58 GMT

Hi,

I am sorry to see that nobody took the time to check your request since a couple of months... Let me try to help you if not too late.

If I understand correctly, you followed the tutorial about the KCS but you scaled down all data using the C-Wizard with a ratio 1/31.6. At the end, you observed a difference in Ct about 3% compared to the full scale results provided by CFD as well. Correct?

I am not really surprised by this difference. It is known that the scaling up/down results is always very risky since turbulence does not act the same way at both scales (indeed, we preserve the Froude number but not the Reynolds number). Also, the scale is here very large and the more we scale, the more difference we can get.

Does that make sense for you?

Best regards,

Benoit

Regarding the calculation of KCS resistance

Halder — Fri, 21 Apr 2023 07:24:30 GMT

I am working on the simulation of the ship modelling. I am using the FINE/Marine software for ship model calculation. Therefore, I am following the tutorial “KCS resistance calculation”. However, I have taken geometry from the FINE/Marine tutorial folder “KCS_hull_SVA_cf_withnames_cf2”. After that I used the model scale without a rudder (1:31.6). Next step I followed the same procedure as mentioned in the report. I have simulated six velocities (0.915m/s-2.379m/s) corresponding to the Froude number and compared them with the results without the rudder at velocity 2.196m/s. In my CFD results I got a Ct value of 3.44*10^3 (Fx=82.24N, wetted surface=9.9206m^2, density 999.1kg/m^3, V=2.196) while the reference Ct value is 3.551*10^3 corresponding velocity 2.196m/s). I am getting a lower Ct value as compared to the FINE/Marine CFD results. So, I am worried about getting a lower Ct value. Therefore, I am requesting you to kindly help with the calculation so I can get similar results as mentioned in the KCS resistance calculation.

RE: Result of calculation in FineTurbo

DenysK — Mon, 24 Jul 2023 11:31:54 GMT

Hi,

My calculation was convergied. I don't remember reached level of convergience.
Disbalance of mass flow between inlet and outlet equals 0.02%. And it looks like horizontal line.

Have you ever checked result calculation at different parameter scales? You need to try to check your results of calculation at different parameter scales.

Regards,

Denys

RE: Result of calculation in FineTurbo

Gaurav — Mon, 24 Jul 2023 11:16:00 GMT

Hi,

This question has also been asked in the CFD online forum. The contours of the compressor can't be like that. Check whether the computation is converged.

Rgds

Multiple Frames in Cf view

sima101f — Mon, 19 Jun 2023 10:39:18 GMT

Hello. Does some know or guide how to create multiple frames in single screen in cfview? for example i want to see my b2b surfaces in b2b view at 10%, 50% and 90% span in single a frame window. So to say three different pictures in a single picture.

Thanks in advance