# model Validation **URL:** \ **Category:** Controls\ **Created:** [November 24, 2017, 7:55am UTC](https://forums.nlr.gov/t/model-validation/1735 "2017-11-24T07:55:52Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![Jason.Jonkman](https://dub1.discourse-cdn.com/nrel/user_avatar/forums.nlr.gov/jason.jonkman/32/3086_2.png) [@Jason.Jonkman](https://forums.nlr.gov/u/Jason.Jonkman)\ **Post date:** [October 19, 2020, 2:06pm UTC](https://forums.nlr.gov/t/model-validation/1735/21 "2020-10-19T14:06:20Z")
Dear Satish, Your waves are not sinusoidal because you’ve enabled second-order wave kinematics. Disabling second-order wave kinematics (WvDiffQTF = WvSumQTF = False) will result in a sinusoidal wave elevation. Best regards, ---
**Author:** ![Satish.Jawalageri](https://avatars.discourse-cdn.com/v4/letter/s/e19adc/32.png) [@Satish.Jawalageri](https://forums.nlr.gov/u/Satish.Jawalageri)\ **Post date:** [October 19, 2020, 4:41pm UTC](https://forums.nlr.gov/t/model-validation/1735/22 "2020-10-19T16:41:42Z")
Dear Jason, Thanks for your reply. Okay, got that. > [@Jason.Jonkman](#): > > Dear Satish, > > OK, thanks for clarifying. > > One big difference I see is that the original OC3 Phase I results for load case 5.1 assumed wave linearity (Airy waves). However, I see that you have enabled second-order wave-kinematics (WvDiffQTF = WvSumQTF = TRUE) in your analysis (hence why your wave elevation is not sinusoidal). The second differences is in regards to wave stretching. The original OC3 Phase I results included Wheeler stretching for the wave kinematics, however, this functionality is not available in the version of OpenFAST that you are running. The lack of Wheeler stretching will impact the wave loads and resulting bending moment at the mudline. > > Best regards, - Does this result attached is correct? (I have attached plots resulted my simulation and the referred simulation results) - Do I get any reference where I can validate this OpenFast model? Thanks, Satish J ![Screenshot (62).png](https://europe1.discourse-cdn.com/nrel/original/2X/0/038b1b7d6cb0deabae6f9e5304261e10a457fa75.png) ![Screenshot (63).png](https://europe1.discourse-cdn.com/nrel/original/2X/8/89284f534f4dfdf08f57a13ac0826727c0abcd54.png) ---
**Author:** ![Jason.Jonkman](https://dub1.discourse-cdn.com/nrel/user_avatar/forums.nlr.gov/jason.jonkman/32/3086_2.png) [@Jason.Jonkman](https://forums.nlr.gov/u/Jason.Jonkman)\ **Post date:** [October 19, 2020, 5:06pm UTC](https://forums.nlr.gov/t/model-validation/1735/23 "2020-10-19T17:06:40Z")
Dear Satish, Your results make sense. You are getting a lower amplitude of mudline fore-aft bending moment because version of HyrdoDyn you are using in OpenFAST does not inherently consider wave stretching, which are included in the results you are comparing to. If you need to match the OC3 results exactly, until wave stretching is added to OpenFAST\*, you could apply wave stretching yourself and use the corresponding wave kinematics within OpenFAST using the WaveMod = 6 option of HydroDyn. This would require that you have wave kinematics at all hydrodynamic analysis nodes along the monopile. Best regards, Footnote: \*NREL did have a project to add wave stretching into OpenFAST, but the project ran out of funding before a successful completion, and the solution was not numerically stable for structural flexible substructures; and we have not yet been funded to restart and finish the project. ---
**Author:** ![Satish.Jawalageri](https://avatars.discourse-cdn.com/v4/letter/s/e19adc/32.png) [@Satish.Jawalageri](https://forums.nlr.gov/u/Satish.Jawalageri)\ **Post date:** [October 20, 2020, 8:18am UTC](https://forums.nlr.gov/t/model-validation/1735/24 "2020-10-20T08:18:40Z")
Dear Jason, Thanks for your reply. Okay, Then Is the solution I obtained is acceptable without wheeler stretching as it is getting difference of around 20000 KNm? Any recommendation on going ahead with this solution or the software version itself (Openfast)? I can use all these in Fastv8 right? If so, could you provide me the link where I can download the Fastv8? Thanks, Satish J ---
**Author:** ![Jason.Jonkman](https://dub1.discourse-cdn.com/nrel/user_avatar/forums.nlr.gov/jason.jonkman/32/3086_2.png) [@Jason.Jonkman](https://forums.nlr.gov/u/Jason.Jonkman)\ **Post date:** [October 20, 2020, 12:26pm UTC](https://forums.nlr.gov/t/model-validation/1735/25 "2020-10-20T12:26:08Z")
Dear Satish, Not including Wheeler stretching will result in a lower amplitude of wave loading. But Wheeler stretching is known to overpredict the wave loading amplitude anyway. I already suggested the use of WaveMod = 6 in OpenFAST as a way to apply stretching, if needed. I don’t see any reason for you to run FAST v8 since you are already running a newer version–OpenFAST. And downgrading to FAST v8 would require some small input file changes. FAST v8 does not support Wheeler stretching either (but FAST v7 did). Regardless, FAST v8 is available here: [drive.google.com/drive/folders/ … sp=sharing](https://drive.google.com/drive/folders/10Pw8zzOr_YqIgtLmq10XhYpdAveKAWAJ?usp=sharing). Best regards, ---
**Author:** ![Satish.Jawalageri](https://avatars.discourse-cdn.com/v4/letter/s/e19adc/32.png) [@Satish.Jawalageri](https://forums.nlr.gov/u/Satish.Jawalageri)\ **Post date:** [October 21, 2020, 8:34am UTC](https://forums.nlr.gov/t/model-validation/1735/26 "2020-10-21T08:34:22Z")
Dear Jason, Thanks for your suggestions. Okay, Could you please give suggestions on how to generate wave kinematics at all hydrodynamic analysis nodes along the monopile? Thanks, Satish J ---
**Author:** ![Jason.Jonkman](https://dub1.discourse-cdn.com/nrel/user_avatar/forums.nlr.gov/jason.jonkman/32/3086_2.png) [@Jason.Jonkman](https://forums.nlr.gov/u/Jason.Jonkman)\ **Post date:** [October 21, 2020, 12:47pm UTC](https://forums.nlr.gov/t/model-validation/1735/27 "2020-10-21T12:47:32Z")
Dear Satish, The hydrodynamic analysis node locations are written to the HydroDyn summary file. You’d presumably need access to a software that can calculate wave kinematics (including stretching) at these locations. NREL has not provided such a software. The HydroDyn module of OpenFAST can output wave kinematics at the various hydrodynamic analysis nodes. So, with a bit a scripting, you could probably output these, apply a stretching theory, and write the stretched wave data to the wave kinematics input file formats the WaveMod = 6 option requires. Best regards, ---
**Author:** ![Satish.Jawalageri](https://avatars.discourse-cdn.com/v4/letter/s/e19adc/32.png) [@Satish.Jawalageri](https://forums.nlr.gov/u/Satish.Jawalageri)\ **Post date:** [October 21, 2020, 4:29pm UTC](https://forums.nlr.gov/t/model-validation/1735/28 "2020-10-21T16:29:26Z")
Dear Jason, Thanks for your suggestions. Thanks, Satish J ---
**Author:** ![Satish.Jawalageri](https://avatars.discourse-cdn.com/v4/letter/s/e19adc/32.png) [@Satish.Jawalageri](https://forums.nlr.gov/u/Satish.Jawalageri)\ **Post date:** [November 3, 2020, 1:24pm UTC](https://forums.nlr.gov/t/model-validation/1735/29 "2020-11-03T13:24:13Z")
Dear Jason, Could I know where can I get the wave kinematics input file format when WaveMod=6. > [@](#): > > Dear Satish, > > The hydrodynamic analysis node locations are written to the HydroDyn summary file. You’d presumably need access to a software that can calculate wave kinematics (including stretching) at these locations. NREL has not provided such a software. > > The HydroDyn module of OpenFAST can output wave kinematics at the various hydrodynamic analysis nodes. So, with a bit a scripting, you could probably output these, apply a stretching theory, and write the stretched wave data to the wave kinematics input file formats the WaveMod = 6 option requires. > > Best regards, Thanks, Satish J ---
**Author:** ![Jason.Jonkman](https://dub1.discourse-cdn.com/nrel/user_avatar/forums.nlr.gov/jason.jonkman/32/3086_2.png) [@Jason.Jonkman](https://forums.nlr.gov/u/Jason.Jonkman)\ **Post date:** [November 3, 2020, 1:36pm UTC](https://forums.nlr.gov/t/model-validation/1735/30 "2020-11-03T13:36:21Z")
Dear Satish, You’ll need 8 files to specify user-generated wave kinematics via WaveMod = 6: 3 for the wave particle velocities (\*.Vxi, \*.Vyi, _.Vyi), 3 for the wave particle accelerations (_.Axi, _.Ayi, .Azi), 1 for dynamic pressure (.DynP), and 1 for the wave elevation (_.Elev). Examples of these files are provided in Test\_004 in the standalone HydroDyn CertTest from FAST v8. The draft HydroDyn User’s Guide and Theory Manual provides some more information on these input files. The HydroDyn archive and documentation from FAST v8 are available on my Google drive: [drive.google.com/drive/folders/ … sp=sharing](https://drive.google.com/drive/folders/1VxgOK7NoFUg9-KZRoYOc1VS9GQFVSnSr?usp=sharing). Best regards, ---
**Author:** ![Satish.Jawalageri](https://avatars.discourse-cdn.com/v4/letter/s/e19adc/32.png) [@Satish.Jawalageri](https://forums.nlr.gov/u/Satish.Jawalageri)\ **Post date:** [November 3, 2020, 1:55pm UTC](https://forums.nlr.gov/t/model-validation/1735/31 "2020-11-03T13:55:02Z")
Dear Jason, Thanks for your reply. Could you please share the Test\_004 in the standalone HydroDyn CertTest from FAST v8 as I couldn’t find the file in which you provided the link below. > [@](#): > > Dear Satish, > > Not including Wheeler stretching will result in a lower amplitude of wave loading. But Wheeler stretching is known to overpredict the wave loading amplitude anyway. I already suggested the use of WaveMod = 6 in OpenFAST as a way to apply stretching, if needed. > > I don’t see any reason for you to run FAST v8 since you are already running a newer version–OpenFAST. And downgrading to FAST v8 would require some small input file changes. FAST v8 does not support Wheeler stretching either (but FAST v7 did). Regardless, FAST v8 is available here: [drive.google.com/drive/folders/](https://drive.google.com/drive/folders/) … sp=sharing. > > Best regards, Thanks, Satish J ---
**Author:** ![Jason.Jonkman](https://dub1.discourse-cdn.com/nrel/user_avatar/forums.nlr.gov/jason.jonkman/32/3086_2.png) [@Jason.Jonkman](https://forums.nlr.gov/u/Jason.Jonkman)\ **Post date:** [November 3, 2020, 1:58pm UTC](https://forums.nlr.gov/t/model-validation/1735/32 "2020-11-03T13:58:46Z")
Dear Satish, HD\_v2.05.00 in the link below is a self-extracting ZIP archive. Once you extract the files, the Test\_004 files should be found in the CertTest directory. Best regards, ---
**Author:** ![Satish.Jawalageri](https://avatars.discourse-cdn.com/v4/letter/s/e19adc/32.png) [@Satish.Jawalageri](https://forums.nlr.gov/u/Satish.Jawalageri)\ **Post date:** [November 3, 2020, 4:10pm UTC](https://forums.nlr.gov/t/model-validation/1735/33 "2020-11-03T16:10:56Z")
Dear Jason, Thanks for your reply. Could I know what does ########## indicate in the input files? Thanks, Satish J ---
**Author:** ![Jason.Jonkman](https://dub1.discourse-cdn.com/nrel/user_avatar/forums.nlr.gov/jason.jonkman/32/3086_2.png) [@Jason.Jonkman](https://forums.nlr.gov/u/Jason.Jonkman)\ **Post date:** [November 3, 2020, 4:14pm UTC](https://forums.nlr.gov/t/model-validation/1735/34 "2020-11-03T16:14:30Z")
Dear Satish, As explained in the HydroDyn documentation, a nonnumeric string in the WaveMod = 6 wave-kinematics files designates that the node is outside of the water at that time step (above the instantaneous water elevation or below the seabed). Best regards, ---
**Author:** ![Satish.Jawalageri](https://avatars.discourse-cdn.com/v4/letter/s/e19adc/32.png) [@Satish.Jawalageri](https://forums.nlr.gov/u/Satish.Jawalageri)\ **Post date:** [November 5, 2020, 12:35pm UTC](https://forums.nlr.gov/t/model-validation/1735/35 "2020-11-05T12:35:21Z")
Dear Jason, Thanks for your reply. Could you please suggest me on which software to use to generate all wave kinematics. Thanks, Satish J ---
**Author:** ![Jason.Jonkman](https://dub1.discourse-cdn.com/nrel/user_avatar/forums.nlr.gov/jason.jonkman/32/3086_2.png) [@Jason.Jonkman](https://forums.nlr.gov/u/Jason.Jonkman)\ **Post date:** [November 5, 2020, 1:01pm UTC](https://forums.nlr.gov/t/model-validation/1735/36 "2020-11-05T13:01:13Z")
Dear Satish, As I mentioned before, NREL has not provided such a software. And we are not in a position to recommend one from elsewhere. Best regards, ---
**Author:** ![Satish.Jawalageri](https://avatars.discourse-cdn.com/v4/letter/s/e19adc/32.png) [@Satish.Jawalageri](https://forums.nlr.gov/u/Satish.Jawalageri)\ **Post date:** [November 5, 2020, 5:40pm UTC](https://forums.nlr.gov/t/model-validation/1735/37 "2020-11-05T17:40:21Z")
Dear Jason, Thanks for your reply. 1. I have generated wave kinematics externally. I have velocities (x,y,z) and acceleration (x,y,z) at each node at each time step. So my doubt is how do I need to consider these values in .Vxi, .Vyi, .Vzi, .Axi, .Ayi, .Azi as each row represents each time step. 2. Can I consider dynamic pressure file (.DynP) as single column of zero as there is no tapered monopile section (no change in diameter of MP)? Thanks, Satish J ---
**Author:** ![Jason.Jonkman](https://dub1.discourse-cdn.com/nrel/user_avatar/forums.nlr.gov/jason.jonkman/32/3086_2.png) [@Jason.Jonkman](https://forums.nlr.gov/u/Jason.Jonkman)\ **Post date:** [November 5, 2020, 7:57pm UTC](https://forums.nlr.gov/t/model-validation/1735/38 "2020-11-05T19:57:13Z")
Dear Satish, It sounds like you have all of the data you need (except dynamic pressure). So, all you should need to do is structure the data into the file format readable by HydroDyn. A monopile with no taper would not need the dynamic pressure, so I agree, you can set those to zero. Best regards, ---
**Author:** ![Satish.Jawalageri](https://avatars.discourse-cdn.com/v4/letter/s/e19adc/32.png) [@Satish.Jawalageri](https://forums.nlr.gov/u/Satish.Jawalageri)\ **Post date:** [November 6, 2020, 1:19pm UTC](https://forums.nlr.gov/t/model-validation/1735/39 "2020-11-06T13:19:52Z")
Dear Jason, Thanks for your reply. Regarding the structuring these files, I have considered columns as nodes and rows as time step. Here, in my case I have 41 nodes and total time 60 sec time step of 0.005sec, so 41 columns and 12001 rows. Is that correct way of structuring? Thanks, Satish J ---
**Author:** ![Jason.Jonkman](https://dub1.discourse-cdn.com/nrel/user_avatar/forums.nlr.gov/jason.jonkman/32/3086_2.png) [@Jason.Jonkman](https://forums.nlr.gov/u/Jason.Jonkman)\ **Post date:** [November 6, 2020, 3:44pm UTC](https://forums.nlr.gov/t/model-validation/1735/40 "2020-11-06T15:44:30Z")
Dear Satish, Yes, that is correct except that there need only be WaveTMax/WaveDT = 12000 rows in your case because no wave kinematics definition is only needed from time = 0 to time = WaveTMax - WaveDT. Best regards, [Previous page](https://forums.nlr.gov/t/model-validation/1735.md?page=1) [Next page](https://forums.nlr.gov/t/model-validation/1735.md?page=3)