From 476d209b92b6d21d84a1f4fa7e32cdf7c7c8c2b9 Mon Sep 17 00:00:00 2001 From: marcvivesmassana Date: Fri, 23 Jan 2026 09:40:17 +0100 Subject: [PATCH 1/2] bet metrics --- .../02.outputs-list/00.output-fields.md | 31 +++++++++++++++++++ 1 file changed, 31 insertions(+) diff --git a/docs/02.simulation-setup/04.output/02.outputs-list/00.output-fields.md b/docs/02.simulation-setup/04.output/02.outputs-list/00.output-fields.md index 58078db..49ced29 100644 --- a/docs/02.simulation-setup/04.output/02.outputs-list/00.output-fields.md +++ b/docs/02.simulation-setup/04.output/02.outputs-list/00.output-fields.md @@ -66,6 +66,37 @@ It should be noted that the relative velocity is zero on no-slip walls that are | `kOmegaSST_hybridModel` | Hybrid RANS-LES output for kOmegaSST solver (supports both DDES and ZDES) | Non-dimensional | | `localCFL` | Local CFL number | Non-dimensional | +### BET Metrics Output Variables + +The `betMetrics` and `betMetricsPerDisk` output fields provide Blade Element Theory (BET) metrics for analyzing rotor and propeller performance. These fields are available when using BET models in volume zones. + +The following variables are included in the betMetrics output: + +1. **`VelocityRelative`** – Relative velocity with respect to the rotating reference frame. The values are non-dimensional. + +2. **`AlphaRadians`** – Local angle of attack in radians. This is the effective angle of attack that the 2D section observes based on the local velocity field. It is used to impose the aerodynamic force according to the predefined 2D polars that are given for alpha~CL, alpha~CD. + +3. **`CfAxial`** – The axial aerodynamic force coefficient imposed on the imaginary blade (the blade is modeled by the blade element theory). The axial force coefficient is computed as: + + $$c_{fa} = c_l \cos(\phi) + c_d \sin(\phi)$$ + + where $c_l$ is the lift coefficient, $c_d$ is the drag coefficient, and $\phi$ is the local flow angle. This coefficient is used to compute the axial force per unit volume applied to the flow field. + +4. **`CfCircumferential`** – The circumferential aerodynamic force coefficient imposed on the imaginary blade. The circumferential force coefficient is computed as: + + $$c_{fc} = -c_d \cos(\phi) + c_l \sin(\phi)$$ + + This coefficient is used to compute the circumferential force per unit volume applied to the flow field. + +5. **`TipLossFactor`** – A factor to model the effect of blade tip. It affects local solidity of the rotor near the tip region. + +6. **`LocalSolidityIntegralWeight`** – is equal to $\sigma W_t$ with $\sigma$ as the local solidity and $W_t$ as the integral weight. The integral weight is the weighting function $W_t(x) = 2\cos^2(\pi x / t)$, with $x$ being the distance in the thickness direction and $t$ being the disk thickness. The local solidity $\sigma$ depends on the BET formulation type: + + - For **BET-Disk**: $\sigma = (N_b \cdot c) / (2\pi r)$, where $N_b$ is the number of blades, $c$ is the chord length, and $r$ is the radius. + - For **BET-Line**: $\sigma = (c / c_{bl}) \cdot \lambda \cdot W_c$, where $c_{bl}$ is a characteristic blade length, $\lambda$ is a factor (e.g., tip loss factor), and $W_c$ is the circumferential weighting function. + +For more details on Blade Element Theory implementation in Flow360, see [XV-15 Rotor Simulation in Flow360 using the Blade Element Theory](https://simcloud-public-1.s3.amazonaws.com/publications/XV-15_Rotor_Simulation_in_Flow360_using_the_Blade_Element_Theory.pdf). + ### Hybrid RANS-LES Output Variables The `SpalartAllmaras_hybridModel` and `kOmegaSST_hybridModel` output fields provide diagnostic variables for hybrid RANS-LES simulations. The specific variables included depend on whether you're using **DDES** (Delayed Detached Eddy Simulation) or **ZDES** (Zonal Detached Eddy Simulation) as the shielding function. From d1a702a763e5e6d425ceb5cb8df0dc01a51c5efd Mon Sep 17 00:00:00 2001 From: marcvivesmassana Date: Mon, 26 Jan 2026 16:04:07 +0100 Subject: [PATCH 2/2] comments --- .../02.outputs-list/00.output-fields.md | 27 +++++-------------- 1 file changed, 7 insertions(+), 20 deletions(-) diff --git a/docs/02.simulation-setup/04.output/02.outputs-list/00.output-fields.md b/docs/02.simulation-setup/04.output/02.outputs-list/00.output-fields.md index 49ced29..623dd42 100644 --- a/docs/02.simulation-setup/04.output/02.outputs-list/00.output-fields.md +++ b/docs/02.simulation-setup/04.output/02.outputs-list/00.output-fields.md @@ -68,34 +68,21 @@ It should be noted that the relative velocity is zero on no-slip walls that are ### BET Metrics Output Variables -The `betMetrics` and `betMetricsPerDisk` output fields provide Blade Element Theory (BET) metrics for analyzing rotor and propeller performance. These fields are available when using BET models in volume zones. +The `betMetrics` and `betMetricsPerDisk` output fields provide Blade Element Theory (BET) metrics for analyzing rotor and propeller performance. These fields are available when using BET models in volume zones. The `betMetrics` field includes data from all BET disks with possible overlapping, while `betMetricsPerDisk` provides separate outputs for each disk to avoid overlap. The following variables are included in the betMetrics output: -1. **`VelocityRelative`** – Relative velocity with respect to the rotating reference frame. The values are non-dimensional. +1. **`VelocityRelative`** – Relative velocity with respect to the rotating reference frame (non-dimensional). -2. **`AlphaRadians`** – Local angle of attack in radians. This is the effective angle of attack that the 2D section observes based on the local velocity field. It is used to impose the aerodynamic force according to the predefined 2D polars that are given for alpha~CL, alpha~CD. +2. **`AlphaRadians`** – Local angle of attack in radians. -3. **`CfAxial`** – The axial aerodynamic force coefficient imposed on the imaginary blade (the blade is modeled by the blade element theory). The axial force coefficient is computed as: +3. **`CfAxial`** – Axial aerodynamic force coefficient. - $$c_{fa} = c_l \cos(\phi) + c_d \sin(\phi)$$ +4. **`CfCircumferential`** – Circumferential aerodynamic force coefficient. - where $c_l$ is the lift coefficient, $c_d$ is the drag coefficient, and $\phi$ is the local flow angle. This coefficient is used to compute the axial force per unit volume applied to the flow field. +5. **`TipLossFactor`** – Factor to model the effect of blade tip. -4. **`CfCircumferential`** – The circumferential aerodynamic force coefficient imposed on the imaginary blade. The circumferential force coefficient is computed as: - - $$c_{fc} = -c_d \cos(\phi) + c_l \sin(\phi)$$ - - This coefficient is used to compute the circumferential force per unit volume applied to the flow field. - -5. **`TipLossFactor`** – A factor to model the effect of blade tip. It affects local solidity of the rotor near the tip region. - -6. **`LocalSolidityIntegralWeight`** – is equal to $\sigma W_t$ with $\sigma$ as the local solidity and $W_t$ as the integral weight. The integral weight is the weighting function $W_t(x) = 2\cos^2(\pi x / t)$, with $x$ being the distance in the thickness direction and $t$ being the disk thickness. The local solidity $\sigma$ depends on the BET formulation type: - - - For **BET-Disk**: $\sigma = (N_b \cdot c) / (2\pi r)$, where $N_b$ is the number of blades, $c$ is the chord length, and $r$ is the radius. - - For **BET-Line**: $\sigma = (c / c_{bl}) \cdot \lambda \cdot W_c$, where $c_{bl}$ is a characteristic blade length, $\lambda$ is a factor (e.g., tip loss factor), and $W_c$ is the circumferential weighting function. - -For more details on Blade Element Theory implementation in Flow360, see [XV-15 Rotor Simulation in Flow360 using the Blade Element Theory](https://simcloud-public-1.s3.amazonaws.com/publications/XV-15_Rotor_Simulation_in_Flow360_using_the_Blade_Element_Theory.pdf). +6. **`LocalSolidityIntegralWeight`** – Local solidity multiplied by the integral weight. ### Hybrid RANS-LES Output Variables