CONTINOUS PARTICLE SIZE (CPS) 連續粒徑

作為CFD軟體的重要功能之一， PreonLab 已於兩年前導入了粒子局部細化功能，可以將運算資源集中在重要關注的區域，支援3個階段的分辨率，中級粒徑為低級粒徑的4倍，高級粒徑為中級粒徑的2倍，換句話說，理論上粒子數的限制為64倍。

PreonLab 不單擴增了分辨率的階段，更是將此限制直接取消，在 5.2 版本中，每個粒子都能設定自身的粒徑，實現了前所未有的幾何適應性，更能幫助粒子在不關注的位置合理的粗化，減少粒子總數，此新功能稱為連續粒徑。

因為CPS使用的求解器是同一個而非被切割成多個求解器，帶來另一個好處是大幅提升了渲染與後處理的生成速度。

Previously, PreonLab supported up to 3 resolution levels:  The middle level had twice the diameter of the finest level and the coarsest level had four times this diameter. This means that the theoretical limit for particle count reduction (and therefore speedup) was 64,  because doubling the particle diameter increases the particle volume by a factor of 8.  One of the most frequent feature requests was the addition of a fourth resolution level, which would increase this factor to 512.

PreonLab 5.2 delivers that but it doesn’t stop here. Instead of adding one more level, we abolished the whole concept of levels. In PreonLab 5.2, every particle stores its own size. This does not only allow for unprecedented adaptivity, it also greatly helps with coarsening. Instead of having to find 8 smaller particles which are combined into a bigger particle, the new coarsening can simply combine any amount of suitable neighboring particles into one. This means that fine particles outside refinement zones are coarsened much faster, reducing the overall particle count. We call this new feature Continuous Particle Size (CPS).

A great side effect of CPS is that usability is also improved. Instead of three solver objects (one for each level), all particles are now contained in a single solver.

MULTIPHASE 多相流

一般來說，執行多相流是比較具挑戰性的，尤其當兩種流體之間的密度比很高時。考慮到這個問題，PreonLab 5.1已經將多相模擬導入，使其以更有效率的方式進行計算，事實證明對於大型齒輪箱以及其高轉速下的模擬結果非常有幫助。

PreonLab 5.2 通過導入新的時間步長設定改進了多相流模擬功能，即使在更困難的計算中也達到模擬的可靠性；另一個新功能允許使用者調整實際體積模數值，提高模擬的精準度，改善工作設定流程。

PreonLab 5.1 has made it possible to perform such multiphase simulations in an efficient way. This has proven to be highly advantageous in order to achieve more realistic simulation results for large gearboxes and for cases where high rotational speeds are involved.

PreonLab 5.2 further improves multiphase simulations by introducing a new time-stepping method, which enhances the reliability of simulations even with more challenging setups.

Another new feature in PreonLab 5.2 allows the usage of real bulk modulus values, which enhances the quality and accuracy of the simulation and improves the workflow by eliminating the need to fine-tune setup parameters.

(影片: https://www.youtube.com/watch?v=S9K2LY8o3qE&t=4s)

THERMODYNAMICS 熱力學

在 PreonLab 5.2 中，新的體積熱源功能被允許在單求解器中設定，另外，平面傳感器也支援輸出實體的計算結果，獲取溫度的截面分布圖。

當溫度變化造成流體密度改變時， PreonLab 5.2 建立更靈活的粒徑調整功能，使模型更能貼近真實。

In PreonLab 5.2, a new heat field feature allows the application of a volumetric heat source on individual solvers. The influence of such a heat field can be controlled either by using a solid as a boundary volume or by employing a point cloud resource object with the relevant spatial sampling points.

Furthermore, Sensor plane objects are now compatible with solid volume solvers. Use it to get cross-sectional information about the temperature distribution, e.g., within the windings of an e-motor.

PreonLab 5.2 includes a new temperature-based density implementation that makes use of the new particle size flexibility to adjust the volume of the particles as a response to density changes. It provides a more realistic model for applications relying on this phenomenon.

WATER WADING SIMULATION WITH AVL VSM 涉水模擬

使用AVL的懸吊系統模型，透過結合PreonLab與AVL VSM，將車輛懸吊系統分為四個區域，單獨定義彈簧與阻尼參數，實現車輛的涉水分析。

車輛在新版本中擁有自身的質量並可以感應軌道的深度，確保輪胎與軌道之間的接觸，無須外部輸入行駛路徑腳本，可通過不平坦的軌道與水流，並擁有虛擬駕駛邏輯與強大的車輛懸吊模型。

With PreonLab 5.2, a new suspension model is made available in PreonLab known as the Vehicle Simulation Model or VSM. This is possible by combining the power of PreonLab with AVL VSM.

This model uses a quarter car approach dividing the suspension of the car into four regions. You can define the spring and damper settings individually for each section.

The vehicle settings, details of the track and the vehicle kinematics are defined in the user interface of VSM. As before, loading the vehicle and track geometries , defining the transformation groups and interconnecting them and setting up the fluid solver are done in PreonLab. The wheels now have its own masses and sense the depth of the track and PreonLab ensures contact between the tyres and the track without having to use an external script.

With PreonLab and AVL VSM at your hand, you can now perform even more sophisticated water wading simulations, considering uneven tracks and crossflows while having a virtual driver and a powerful car suspension model.

(影片:https://www.youtube.com/watch?v=DNpsjdFnGis)

USABILITY & WORKFLOW 可用性與工作流程

在 PreonLab 5.2 中，引進針對CAD文件格式的支援，尤其是通用的STEP文件也能直接匯入，相較於傳統基於網格的文件格式(如STL)，STEP格式的檔案大小更具競爭力，更不用擔心幾何數據匯出時後造成加載時間過長。

內建一個預設的材料性質資料庫也是使用者經常回饋的需求， PreonLab 5.2 中，您可以選擇定義以及保存任何材料性質，並分享給其他使用者。

關於其他更多更新內容或資訊，可以查看更新後的使用手冊。

With PreonLab 5.2, we introduce native support of CAD file formats, in particular the popular STEP file format. The STEP file format benefits from a smaller file size compared to conventional mesh-based file formats such as STL due to its representation of the raw geometry data, but suffers from a longer loading time due to the necessary tessellation of the geometry data. Therefore, we have combined different concepts in order to give you the option to convert the imported CAD file into our very own PRMESH file format, which consumes even less hard drive space while loading blazing fast.

Having a material library offering presets has been a frequent request. With PreonLab 5.2 you now have the option to easily define and save your material settings for any object. Make sure you also share those valuable settings with you colleagues – sharing is caring.

新版PreonLab 5.2 無網格光滑粒子流場分析 總結:

• 連續粒徑:自由設定粒徑且靈活調整粗細,大幅提升渲染與後處理的生成速度。
• 多相流-導入新的時間步長設定且允許使用者調整實際體積模數值,提高模擬的精準度。
• 熱力學-增強的傳感器功能和靈活的粒徑調整功能，使模型更能貼近真實。
• 涉水模擬-車輛的涉水分析並擁有虛擬駕駛邏輯與強大的車輛懸吊模型。
• 可用性與工作流程-支援CAD文件格式匯入,數據檔案小且快速匯出。在材料性質資料庫中更加方便獲取正確的數據。

想更清楚的了解 新版PreonLab 5.2 無網格光滑粒子流場分析 的細節，歡 迎 來 電 (02)2712-8448 或是 來 信。

If you want to know more details from PreonLab 5.2 ,please contact Simhex.

• 延伸閱讀
  • AVL PreonLab 5.1 Release
  • AVL PreonLab 無網格CFD模擬技術
  • 新版 PreonLab 5.1 發布: 更貼近真實應用

這篇文章 新版PreonLab 5.2 無網格光滑粒子流場分析 最早出現於 星恆科技有限公司。