Mr. Heinrich von Zadow

Hi Carlos, I think I remember these black BReps from the good old CAESES4 days 😉 If I recall correctly this happens when importing IGES/STEP from certain other CAD tools and can be easily resolved by just assigning a different color to the imported parts. Since they are currently black, you would have to use the BRep operation "remove colors" first and then assign a different color... Best regards, Heinrich

Hi Ravi, sweet! Happy to see that you arrived at a design you are happy with so quickly. If you don't mind attaching your project here, I could take a look into the hub shape. Cheers, Heinrich

Hi Andreas, maybe I am missing the point, but where exactly does CAESES come in here? If you think there is anything our software can help you with, feel free to get in touch! Anyway, I guess my next try would be a STEP export. Also make sure to use the same units with both tools so you don't run into trouble with tolerances. Cheers, Heinrich

Hi Milad, very good! Yes, you can export the content of tables to csv like this: If you want to plat any of the other designs (i.e. the "finaldata" designs returned by dakota) you would have to do the formatting by yourself. Cheers, Heinrich

Hi Yuwen, at this moment we don't really have this kind of functionality. However, you might want to check again after the next release 😉 In the meantime I attached a quicksort algorithm feature from this old post from Arne: Cheers, Heinrich quicksort.fdf

Hi Alexis, the documentation can be searched i.e. for "String" which pops up all the corresponding class functions. You should be able to achieve what you are looking for with the replaceByString command: The problem with the backslash symbol is, that it is also used as an escape character. Therefore you need to use a little workaround e.g. as follows: FString s("a/b") s.replaceByString("/","\?") s.replaceByString("?","") Cheers, Heinrich

Hi Yuwen, it usually means that you try to modify an object that you are not allowed to (in order to prevent recursion). If you just need the max value, you could (inside a feature) use a doubleSeries like this: FDoubleSeries values([1,2,3,4,5,4,3,2,1]) FDouble maxVal(values.getMax()) Cheers, Heinrich

Hi Milad, there is no option to visualize them currently -- we are definitely planning to introduce that at some point though. The finaldata file (especially, if you choose a high number of "solutions considered") basically contains the points that lie -- according to the model -- on the pareto frontier. However, the results will definitely be improved a lot if you integrate your calculations into CAESES. The design engine would then automatically verify these candidates and add the new results to the model. This will not just increase the accuracy of the model, but it will do so particularly in the region of interest --> that' why we see such fast convergence with this optimization technique in many cases. Cheers, Heinrich

Hi Milad, yes, that's exactly what I did. Is there any particular reason why you are using 4.4? If you set up a Dakota Design Engine with the method "Global Optimization on Response" you can choose to use the existing result pool and when you start the Design Engine you can select the table you have just imported. Dakota will then generate a surrogate, run an optimization on it and return the predicted optimum (or multiple pareto-optimal designs in case you have a multi-objective problem and specify "solutions considered" > 1). You can look at the predicted optima in the "finaldata" file in you result directory. The procedure described above is more like a work-around. Usually the idea is, to couple your simulation tool with CAESES and then have the predicted optima evaluated automatically through CAESES. The surrogate model would then be re-generated with the new variants which increases the accuracy of the prediction. The procedure then repeats... Cheers, Heinrich

Hi Milad, that looks to me as if you have generated these results manually (or through a different tool/script)? Usually, when you set up your design in CAESES and run the simulations through one of the optimization engines, you will have a result table which you can use right away. Alternatively, you could always use Dakota/Surfpack though the command line... In your case, with some changes to the formatting (I did a quick search and replace of \t\t with \t to get rid of the double-tabs), you should be able to import the existing results into CAESES and create a Surrogate aka. Response Surface Model from them. I quickly did that to take a look at the data -- see attached project file. To get a good fitting Surrogate I recommend using a more suitable sampling algorithm (usually Latin Hypercube or Sobol is what we recommend, Adaptive Sampling would be the more advanced option). For the model itself, there are different options available (Kriging works well for most cases I came across recently but depending on your problem you might also want to try out Artificial Neural Networks or Radial Basis Functions...). For now, the parameters y1 and y2 are just dummies, so they do not return the correct evaluation. However, you can still run an optimization on the existing results and then look into the generated "finaldata1" file to check the predicted optimal designs. As I didn't know better, I specified to minimize y1 and y2 and attached the results. You can easily change that in the Dakota Design Engine. These are the predicted optimal candidates: Hope this gives you a good point to start. Cheers, Heinrich importTable.cdb

Hej Ravi, I don't think that the Torqeedo props are a standard series. Might be that they use some well known section definitions but I don't think they share these information. Designing something that looks roughly like the picture (at least the outlines) will be easy, but you cannot expect to get proper performance this way. What I'd recommend at the very least is, to use a suitable series for the sections (Naca66mod could be a good starting point. Might be that you have to thicken it a little more if you are going for a 3D print), find out the pitch of the original (or, even better the pitch that suits your needs) and then use the propeller sample project that comes with CAESES to adjust chord, skew, pitch etc. distributions along the radius. Cheers, Heinrich

Dear Christina, what is shown in the video is just an example of parametric geometry modelling. In CAESES you typically define parameters to be used within your model. If you change their values, the geometry is changed as well, depending on how you used them. Parameters can not just hold double values, but also complex expressions (mathematical and also wrt. other objects in your project). In addition, any parameter can be turned into a DesignVariable (just select it and click the check box in the object editor). Design Variables can NOT hold expressions, but just doubles (or integers, if specified) and additional lower and upper bounds. The main point here is that Design Variables are the type you use if you want to automatically change their values through a Design Engine (like an optimization algorithm that changes the DVs to modify the geometry to find the optimum shape...) Hope this clarifies things a bit for you. You will also find detailed explanations, as well as samples and tutorials in the CAESES documentation. Cheers, Heinrich

Hi Carlos, in this case you might just want to visit our website and download the latest CAESES5 release: https://www.caeses.com/downloads/ cheers, Heinrich

Hi Carlos, could you please update to the latest release and check if the problem persists? Cheers, Heinrich

Hi Assiouras, it's quite simple: fdb is the file format of the CAESES4.x and older releases, while cdb is the current format of CAESES5.x. There is no backwards compatibility (you can open an fdb in CAESES5 and save it as cdb, but not the other way around), hence the different file type. In addition, anything with an additional "c" indicates a non-commercial license and therefore cannot be opened with a commercial license. Best regards, Heinrich

Hi Armagan, I took a look at the project. From what I could see, the solid blade was not generated correctly. I adjusted a few settings as follows: From there it looks as as if everything works well and you get the correct flow domain: Cheers, Heinrich WindTurbineAE.cdbc

Dear Armagan, generally speaking, CAESES 5 offers backwards compatibility -- you should be able to open files from CAESES 4, but not the other way around. However, there have been some changes to Feature Definitions and also to the CAD Kernel which might needs some small adjustments in the projects to make it work in CAESES 5. If you can share the project, I could take a look. Best regards, Heinrich

Dear Atiyah, you are very welcome. About the file you might want to get in touch with my colleague Daehwan Park -- his mail is shown in the screenshot you sent. Best regards, Heinrich

Dear Nuttarat, I am sorry that I didn't find some time to look into this earlier. From what you have sent, it can be seen, that the discontinuity in the rail of your surface causes the irregularities: If you replace this rail with a continuous version that looks somewhat like this, the surface quality already gets much better: In a BRep, you can now simply extend this surface and trim it at the symmetry plane: It is far from perfect, but hopefully a good starting point for you... Cheers, Heinrich Waterjet_intake_Diffuser_HvZ.fdbc

Hi Atiyah, the working mechanism ist the same for both (actually, the Lackenby is also a Delta Shift). A function is defined along the ship which defines by how much the geometry is shifted at the respective longitudinal position. As you can imagine, this easily allows to shift the longitudinal center of buoyancy and adjust the displacement. Since this is such a common task in hull design, we offer the Lackenby which allows you to manipulate prismatic coefficient (CP) and longitudinal center of buoyancy (LCB) simultaneously. So basically, there is no difference except that you can use the Lackenby if this is what you need, or alternatively set up the geometry variation all by yourself through a standard Delta Shift... E.g. you could also use a delta shift to move the design waterline up and down without changing the height of the hull... A typical scenario of the Lackenby being used in an optimization would be to fix LCB and CP all the while the geometry is modified. This way, you can better compare the different geometry variants on a "fair" level (Otherwise you would often just find that the geometry variant with lowest displacement has lowest resistance, which is usually not what you where looking for...). Also, often times these two measures are fixed constraints, anyways... Like said, there is a Tutorial that covers the complete setup. Cheers, Heinrich

Dear Anand, I took a look at the hull surface you started with. The control polygon looks a bit distorted. I suggest, you sort that out first -- especially the bow region seems to have some folding issues, as you can tell from the attached screenshots. After adjusting the control polygon in this region a little and sorting out a few other things (which probably won't occur if you start with a better surface right away) I managed to get everything to work as intended, although you might want to spend some more time on the fairing! Most importantly you should focus on getting the control points shown in the following picture into a straight line (the middle one is the corner of the surface and there is one point currently very close to it, which needs to be exactly the same!) To adjust the control points, you can use the edit mode: I also moved the project to our latest release of CAESES5 which is why the file type is now a *.cdbc. Cheers, Heinrich NPL hull.cdbc

Hi Atiyah, I would recommend that you take a look at the Lackenby (there is also a tutorial "Lackenby Hull Variation"). It is a partially parametric modelling technique that allows you to set both, longitudinal center of buoyancy and prismatic coefficient (and thereby displacement) at the same time. Best regards, Heinrich

Hi Christina, what you need is a design variable that gives you control over the volume, without changing the length. i.e. the beam of the bulbous bow should work fine. You then need to set up a nested optimization (for example a Brent) that adjusts the beam to match the target volume. You should find plenty of material about these so called "nested optimizations" if you search the forum. Cheers, Heinrich

This might not be the perfect forum for this kind of question since CAESES is not a CFD tool, but rather a parametric CAD and optimization platform that allows you to connect any CFD (or other external) software. However, as far as I know, there is -- and has been for a long time -- extensive research carried out in the field of alternative surfaces both on micro and macro scale. Whether you would actually model these things (e.g. fish-like scales or certain roughness and patterns) or just treat them specifically in your CFD code via boundary conditions depends. Both ways are feasible and have their pro's and con's. Cheers, Heinrich

Dear RWM, please provide some more information so that I can understand what you are having trouble with. Best regards, Heinrich