scholarly journals Numerical simulation of a tropical Storm boundary layer

MAUSAM ◽  
2021 ◽  
Vol 43 (3) ◽  
pp. 259-268
Author(s):  
J.C. MANDAL
Keyword(s):  
Boundary Layer ◽  
Inner Core ◽  
Outer Region ◽  
Vertical Direction ◽  
Tropical Storm ◽  
Surface Boundary ◽  
Surface Boundary Layer ◽  
Non Linear ◽  
Linear Differential ◽  
Coefficient Of Viscosity

A model has been designed to study the surface boundary layer of a tropical storm. The numerical method consists of solving a two point boundary value problem for two systems of simultaneous non-linear differential equations by finite differences. A Stoke's stream function suitable to represent the flow both in interior and exterior regions of a tropical storm boundary layer has been developed. The advantage of the method is that the, boundary layer of the tropical storm can be studied starting from the outer region to the centre of the storm without neglecting non-linear terms. In addition, there IS no need for assumptions on the vertical profiles for tangential and radial velocities. The method is stable and converges within a few iterations. The flow above the friction layer is represented by a steady axisymmetric vortex in gradient balance. To investigate the effect of turbulence- on boundary layer characteristics, turbulence has been represented by four different variations of the eddy coefficient of viscosity with no slip boundary conditions. Computations have been performed 1aking 40-grid points in the vertical direction. It is observed that, if the eddy coefficient of viscosity is assumed to vary with the superimposed flow above the boundary layer, the solutions compare favourably well with observations. The solution also shows an outflow from the Inner core of the boundary layer which is necessary for creation of an eye of the storm.

scholarly journals A Non-Linear Mixed Spectral Finite-Difference 3-D model for planetary boundary-layer flow over complex terrain

2011 ◽  
Vol 6 (1) ◽  
pp. 75-78 ◽  
Author(s):  
W. Weng ◽  
P. A. Taylor
Keyword(s):  
Boundary Layer ◽  
Finite Difference ◽  
Planetary Boundary Layer ◽  
Boundary Layer Flow ◽  
Complex Terrain ◽  
Surface Boundary ◽  
Surface Boundary Layer ◽  
Non Linear ◽  
Flow Over Topography ◽  
Layer Flow

Abstract. The Non-Linear Mixed Spectral Finite-Difference (NLMSFD) model for surface boundary-layer flow over complex terrain has been extended to planetary boundary-layer flow over topography. Comparisons are made between this new version and the surface layer model. The model is also applied to simulate an Askervein experimental case. The results are discussed and compared with the observed field data.

Prediction of Atmospheric Turbulence Characteristics for Surface Boundary Layer using Empirical Spectral Methods

2020 ◽  
Author(s):  
Yagya Dutta Dwivedi ◽  
Vasishta Bhargava Nukala ◽  
Satya Prasad Maddula ◽  
Kiran Nair
Keyword(s):  
Boundary Layer ◽  
Time Series ◽  
Surface Roughness ◽  
Wind Speed ◽  
Atmospheric Turbulence ◽  
Surface Boundary ◽  
Low Frequencies ◽  
Surface Boundary Layer ◽  
Power Spectral ◽  
Mean Wind Speed

Abstract Atmospheric turbulence is an unsteady phenomenon found in nature and plays significance role in predicting natural events and life prediction of structures. In this work, turbulence in surface boundary layer has been studied through empirical methods. Computer simulation of Von Karman, Kaimal methods were evaluated for different surface roughness and for low (1%), medium (10%) and high (50%) turbulence intensities. Instantaneous values of one minute time series for longitudinal turbulent wind at mean wind speed of 12 m/s using both spectra showed strong correlation in validation trends. Influence of integral length scales on turbulence kinetic energy production at different heights is illustrated. Time series for mean wind speed of 12 m/s with surface roughness value of 0.05 m have shown that variance for longitudinal, lateral and vertical velocity components were different and found to be anisotropic. Wind speed power spectral density from Davenport and Simiu profiles have also been calculated at surface roughness of 0.05 m and compared with k−1 and k−3 slopes for Kolmogorov k−5/3 law in inertial sub-range and k−7 in viscous dissipation range. At high frequencies, logarithmic slope of Kolmogorov −5/3rd law agreed well with Davenport, Harris, Simiu and Solari spectra than at low frequencies.

scholarly journals A global perspective on Langmuir turbulence in the ocean surface boundary layer

2012 ◽  
Vol 39 (18) ◽  
Author(s):  
Stephen E. Belcher ◽  
Alan L. M. Grant ◽  
Kirsty E. Hanley ◽  
Baylor Fox-Kemper ◽  
Luke Van Roekel ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Ocean Surface ◽  
Global Perspective ◽  
Surface Boundary ◽  
Langmuir Turbulence ◽  
Surface Boundary Layer

LESbrary: A library of large eddy simulation data for the calibration and uncertainty quantification of ocean surface boundary layer turbulence parameterizations

2021 ◽  
Author(s):  
Gregory Wagner ◽  
Andre Souza ◽  
Adeline Hillier ◽  
Ali Ramadhan ◽  
Raffaele Ferrari
Keyword(s):  
Boundary Layer ◽  
Turbulent Mixing ◽  
Large Scale ◽  
Ocean Surface ◽  
Limited Area ◽  
Surface Boundary ◽  
Model Errors ◽  
Surface Boundary Layer ◽  
Large Eddy ◽  
Free Parameters

<p>Parameterizations of turbulent mixing in the ocean surface boundary layer (OSBL) are key Earth System Model (ESM) components that modulate the communication of heat and carbon between the atmosphere and ocean interior. OSBL turbulence parameterizations are formulated in terms of unknown free parameters estimated from observational or synthetic data. In this work we describe the development and use of a synthetic dataset called the “LESbrary” generated by a large number of idealized, high-fidelity, limited-area large eddy simulations (LES) of OSBL turbulent mixing. We describe how the LESbrary design leverages a detailed understanding of OSBL conditions derived from observations and large scale models to span the range of realistically diverse physical scenarios. The result is a diverse library of well-characterized “synthetic observations” that can be readily assimilated for the calibration of realistic OSBL parameterizations in isolation from other ESM model components. We apply LESbrary data to calibrate free parameters, develop prior estimates of parameter uncertainty, and evaluate model errors in two OSBL parameterizations for use in predictive ESMs.</p>

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